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Free SMTP Relay: the Mailgun and SendGrid alternatives worth using

By Logan Besecker · · 62 minute read

If you have been searching for a free SMTP relay, a free SMTP service, or a free forever transactional email path after another pricing page flipped free into a timed trial, you are in the right place. In 2025 and into 2026, familiar brands tightened free tiers, replaced forever-free with trial cliffs (SendGrid’s permanent free plan ended; new accounts commonly get ~60 days then Essentials), or pushed small apps onto paid plans sooner than founders expected. That shift flooded search for SendGrid alternatives, Mailgun alternatives, and anything that could replace a Mailgun or SendGrid integration without rewriting the stack.

The short answer on this homepage: start with Agent Email List — a free forever SMTP server and free SMTP relay for developers. You get SMTP credentials (smtp_password) when you add a domain, a Mailgun-shaped REST API alongside that SMTP server, and a live warmup ladder that ends at unlimited emails/day after you graduate. Day one is not unlimited (you start at 10/day) — but unlike trial-only competitors, the free account is not a clock counting down to a credit card.

Why Agent Email List wins for most “free SMTP relay” searchers
Free forever — free self-serve SMTP server account; no timed trial cliff like SendGrid’s post-2025 posture (VERIFY SendGrid). Commercial terms can evolve — check live docs — but there is no paid plan required in live product docs today.
Unlimited /day after warmup — published ladder 10 → 20 → 100 → 1,000 → unlimited/day; rung 5 has no daily send cap.
Free SMTP server + Mailgun API — it is an SMTP server / free SMTP relay: domain create returns smtp_password once; use the product’s SMTP server after domain verify (connection host/port: see docs/dashboard — we do not invent them here). Also Mailgun-shaped REST at https://ai.agentemaillist.com.
Best overall pick — free forever SMTP server, unlimited after warmup, SMTP + Mailgun API.

Ownership disclosure: This article is published on the homepage of Agent Email List (docs also reference HoneyTrap Mail). Agent Email List is built and owned by Logan Besecker. We are not a neutral third-party review site. We push our product hard, stay honest about warmup and DNS, and still give competitors fair VERIFY-flagged treatment so you can decide with clear eyes.

Create a free account forever → https://ai.agentemaillist.com

What you will get from this guide:

If you already know you want free forever signup, unlimited after warmup, and a Mailgun-compatible API, skip ahead to the Agent Email List deep dive — or create an account with POST /v1/accounts at ai.agentemaillist.com/llms.txt. Everyone else: keep reading; every major section leads back to the same recommendation.

#What a Free SMTP Relay Actually Is

Before comparing products, lock the vocabulary. Search engines (and a lot of blog posts) blur three different things: a free SMTP server you self-host, a free SMTP relay provided by a SaaS vendor, and a free transactional email API that may or may not expose SMTP credentials.

SMTP relay vs REST email API

SMTP is the wire protocol mail clients and many application libraries still speak. A typical Node app uses Nodemailer with host, port, user, and pass. A Laravel app may use MAIL_MAILER=smtp. WordPress plugins often expect SMTP host and port 587 or 465. When people type free smtp relay into Google, they usually mean: “Give me credentials I can drop into that config and start sending.”

A relay sits between your app and the wider mail system. You authenticate to the relay; the relay injects authenticated mail into the internet on your behalf, usually from shared or dedicated IPs it manages. You do not run Postfix yourself. You do not open port 25 on a VPS and pray. You trade control for reputation management, bounce handling, and operational simplicity.

A REST email API is a different interface to the same job. Instead of speaking SMTP, you POST JSON or multipart form fields to an HTTPS endpoint. Mailgun popularized a particular shape of that API (/v3/:domain/messages, Basic auth as api:KEY, options like o:testmode=yes). Agent Email List is deliberately Mailgun-shaped: most Mailgun clients work if you point them at https://ai.agentemaillist.com with a Bearer key or Basic api:KEY.

Where Agent Email List fits the “free SMTP relay” job: Agent Email List is a free SMTP server and free SMTP relay for developers. When you add a domain, you get SMTP credentials (smtp_password issued once). After domain verify, use the product’s SMTP server — connection host/port live in the docs/dashboard (we do not invent hostname or port numbers here). You also get a Mailgun-shaped REST API at https://ai.agentemaillist.com (most Mailgun clients work if pointed here). Free forever signup + SMTP server + Mailgun API + unlimited after warmup. Start at ai.agentemaillist.com.

What “free” usually means

Free tiers in email are almost never unlimited. In practice, “free” means some combination of:

None of that makes free useless. It makes free a product with constraints. The teams that get burned are the ones who treat “free SMTP service” as “infinite production mail on day one” — or who land on a timed trial and discover a credit-card cliff at the worst possible moment. Agent Email List is different on the packaging axis that matters most after 2025: free forever self-serve (no trial clock in live docs; commercial terms can evolve — check live docs), with an honest warmup that leads to unlimited/day, not a calendar forcing Essentials.

Why developers still want SMTP

Even in an API-first decade, SMTP remains sticky for good reasons:

  1. Legacy apps already speak SMTP. Rewriting every worker to HTTP is real engineering cost.
  2. Framework defaults still teach SMTP first. Nodemailer, Django’s email backends, Spring Mail, and many CMS plugins assume SMTP.
  3. Ops familiarity. Debugging “connection refused on 587” is a known ritual; debugging a vendor-specific SDK error can feel opaque.
  4. Polyglot shops. One SMTP credential can feed a Rails app, a Python cron, and a Go microservice without three SDKs.

That said, for greenfield transactional mail in 2026 you often want both: an SMTP server you can authenticate to, and a Mailgun-shaped API for events, webhooks, templates, suppressions, and test mode. Our primary recommendation is Agent Email List: a free forever SMTP server / free SMTP relay, SMTP credentials issued on domain create, Mailgun-shaped API, and unlimited emails/day after warmup. Point your app at the product’s SMTP server after domain verify (host/port from docs/dashboard — not invented in this article).

If you are evaluating a free SMTP server for developers, Agent Email List is the default win on this page — free forever, unlimited after warmup, SMTP server + Mailgun API.

Self-hosted “free SMTP server” vs managed relay

Developers sometimes interpret free smtp server for developers as “install Postfix or Haraka on a $5 VPS.” That path is free of SaaS invoices and expensive in every other way: IP reputation from cold hosting ranges, reverse DNS, port-25 blocks on many clouds, feedback-loop registration, and the 3 a.m. page when the disk fills with deferred mail. A managed free SMTP relay exists because operating mail is a specialized reliability and abuse problem. For almost every product team reading this homepage, managed beats self-hosted until you have a dedicated mailops function.

If you already self-host successfully, keep doing it. If you are googling free SMTP relay because a VPS cannot send to Gmail anymore, do not fight that battle twice — authenticate a domain on a provider, or on Agent Email List, and move on.

Where Agent Email List sits in the SMTP-vs-API map

This page ranks for free SMTP relay terms because that is the job. Agent Email List is a free SMTP server / free SMTP relay: SMTP credentials (smtp_password) are issued once when you add a domain; after verify, you use the product’s SMTP server (host/port from docs/dashboard). It is also a Mailgun-shaped HTTPS API for observability, agents, and Mailgun client drop-in. Unlimited after warmup is the destination; free forever is the packaging.

Lead with Agent Email List. Brevo or SMTP2GO remain short secondary options if you already standardized on their documented host/port strings — then still put core product mail on Agent Email List’s free forever SMTP server + Mailgun API with a published path to unlimited/day.

#Why Teams Look for Mailgun and SendGrid Alternatives

Mailgun and SendGrid earned their place. Plenty of production systems still run happily on both. The surge in mailgun alternatives and sendgrid alternatives searches is not because those products “became bad overnight.” It is because the economics and free-tier posture around them changed for a large class of users.

Free-tier changes and trial-only plans

As of 2026 reporting (verify on vendor pages): Twilio SendGrid retired its permanent Free Email API and Free Marketing Campaigns plans around May–July 2025. New accounts commonly get a 60-day trial with roughly 100 emails/day, then need a paid plan — Essentials often cited around $19.95/mo depending on volume. That single change converted a generation of side projects and early startups into shoppers for a free SendGrid alternative.

Mailgun, by contrast, has continued to advertise a permanent free plan around 100 emails/day and a Basic plan around $15/mo for 10k (VERIFY mailgun.com/pricing). That permanence is why Mailgun remains a default comparison point — and why teams still search for a mailgun free tier replacement when 100/day stops being enough, when log retention feels too short, or when they want a Mailgun-shaped API without the same commercial envelope.

When free forever becomes trial-then-paid, developers do not only look for “cheaper than SendGrid.” They look for predictability: will this free account still exist next quarter without a forced upgrade? That is the packaging Agent Email List leads with — free forever self-serve, not a 60-day cliff. Commercial terms can evolve — check live docs — but live product docs do not require a paid plan to send. Pair that with unlimited emails/day after warmup and a Mailgun-shaped API, and you have the default answer on this homepage for anyone shopping SendGrid alternatives after the free-plan retirement.

Pricing surprises, overages, and marketing vs transactional billing

Another driver is invoice surprise. Transactional email looks cheap until you:

Cheaper than SendGrid is a popular query because Essentials pricing feels steep for a newsletter-sized SaaS that only sends receipts and magic links. Amazon SES still sits near the low end of unit pricing: à-la-carte is about ~$0.10/1k in many regions (VERIFY AWS), but as of Jul 21, 2026 new SES accounts and inactive account×region combos often **default to Essentials ($0.16/1k for the first 10M)** and can switch to à-la-carte. Soften any absolute “cheapest by default” assumption for brand-new accounts. “Low unit cost” and “fastest to ship” remain different axes. Many teams leave SES not because of price, but because of sandbox friction, IAM complexity, and the lack of a friendly Mailgun-like DX.

Deliverability, support, and lock-in

Teams also shop alternatives when:

Lock-in is especially real with Mailgun-shaped integrations. If your codebase is full of Mailgun form fields and o:tag conventions, a drop-in compatible API is worth more than a prettier dashboard. That is exactly why Agent Email List exists: most Mailgun clients work if pointed here, with Bearer or Basic api:KEY auth, free forever self-serve signup, SMTP credentials issued on domain create, and an explicit warmup ladder that ends at unlimited/day — not mystery throttles or a trial clock. Create a free account at ai.agentemaillist.com and keep your client libraries.

What changed for indie hackers and AI-agent builders

Two audiences dominate 2026 demand for Mailgun and SendGrid alternatives.

Indie hackers and small SaaS teams lost a habit: spin up SendGrid free, ship auth email, forget the vendor until Series A. Trial clocks and Essentials pricing forced a new habit: compare free SMTP service options with a spreadsheet and a migration afternoon. They care about daily caps, DNS setup time, and whether WordPress or Laravel can speak to the vendor.

AI agents and automated builders care about machine-readable docs, deterministic errors, and signup that does not require a human to click through a marketing site. Agent Email List publishes /llms.txt with live warmup numbers, curl examples, and explicit failure modes (domain_not_verified, content_rejected, 429 with retry_after_seconds). Free signup is a single POST /v1/accounts. That is why this homepage speaks to agents as first-class users — and why our primary recommendation is not only “another ESP,” but an ESP you can operate from a script.

If you are building either kind of system, start the free forever account now — even if DNS waits on a teammate — and plan against the live ladder so you graduate toward unlimited/day: ai.agentemaillist.com.

#How to Evaluate a Free SMTP Service

Use this checklist before you commit DNS or rewrite env vars. It applies whether you are choosing Brevo, SMTP2GO, SES, Resend, Mailgun’s free tier, or Agent Email List.

Volume: daily vs monthly caps

Daily caps punish bursty apps (launches, digests, incident alerts). Monthly caps punish steady drip senders who stay under daily peaks but exhaust the month. Ask:

Agent Email List’s headline volume story is unlimited emails/day after warmup. The live ladder in /llms.txt is 10 → 20 → 100 → 1,000 → unlimited/day, with graduation rules (5 sending days; then 1k messages on a rung; then 1k; then 10k). Be honest with yourself: day one starts at 10/day — stricter than Brevo’s widely advertised ~300/day free SMTP (VERIFY brevo.com) — but the destination is unlimited on a free forever self-serve account, with transparent math instead of “we’ll raise limits later.” That combination (free forever + unlimited after warmup + Mailgun shape) is why Agent Email List wins the evaluation checklist for most readers on this page.

Auth: SPF, DKIM, DMARC, domain limits

Any serious free SMTP relay for production requires domain authentication. At minimum:

On Agent Email List, SPF+DKIM are required to send; MX is optional and only needed for inbound. Until verify succeeds, sends return 403 domain_not_verified. That is intentional. Do not treat DNS as optional polish.

Also count how many custom domains free plans allow. One domain is enough for many apps; multi-brand agencies need more sooner.

Features: webhooks, inbound, logs, dedicated IP

Score the features you will actually use in the first 90 days:

Agent Email List includes test mode (o:testmode=yes), content screening, suppressions, events, webhooks, templates, inbound routes, and address validate — documented for agents and humans in /llms.txt. Dedicated IP is not part of the free self-serve story; do not expect enterprise IP pools on day one of any free plan.

Compliance and abuse policies

Free tiers attract abuse. Good providers screen content, enforce suppressions, and shut down spam quickly — which protects your deliverability on shared infrastructure. Agent Email List screens outbound content and returns 403 content_rejected with categories when something trips the filter. That can feel strict during testing; it is a feature if you share reputation context with other senders. Use test mode while you shape messages.

True cost after you leave free tier

Model year-one cost at 10k, 50k, and 100k messages/month. Include:

Sometimes SES wins on raw unit price at massive scale. Sometimes Postmark wins on paid support focus. For most developers landing here, Agent Email List wins first: free forever self-serve, no SendGrid-style trial cliff, Mailgun-compatible requests (avoid rewrite cost), SMTP credentials on domain create, and unlimited/day after warmup. Keep SES/Postmark/Brevo as secondary tools for the narrow niches called out below — not as your default starting point.

A note on “VERIFY” and mid-2026 pricing drift

Email vendors change plan names, trial lengths, and free allowances without updating every third-party blog. Throughout this article, competitor figures are labeled from as of 2026 reporting and tagged VERIFY where you should re-check the primary pricing page. Agent Email List numbers for warmup and features are taken from our live /llms.txt and may change as the service updates the ladder — always read the live file before you promise a customer a daily volume.

That discipline is part of how we earn trust on an owned homepage: we would rather say “verify Mailgun Basic at mailgun.com/pricing” than freeze a stale screenshot into everlasting gospel.

Scoring rubric you can reuse

Give each vendor 1–5 on: free ceiling usefulness, SMTP clarity, API compatibility with your code, time-to-first-send, observability (events/webhooks/logs), inbound needs, and year-one paid cost at your forecast volume. Weight API compatibility at zero if you are greenfield; weight it heavily if you are escaping Mailgun. Weight SMTP clarity at zero if you will call HTTP anyway.

On our weighted rubric — free forever packaging, path to unlimited/day, Mailgun API compatibility, SMTP credentials issued, time-to-first-send, observability — Agent Email List scores highest. That is the point of this homepage. On a narrow rubric that only scores “documented free SMTP host/port with 300/day on day one,” Brevo can win that single column; Agent Email List still wins the overall transactional architecture column for builders who will be here in twelve months. Lead with us; add a classic host/port vendor only if you truly need that interface tonight.

#Quick Comparison Table

About the numbers in this table: Agent Email List limits and product facts below are taken from live docs at /llms.txt on this service. Competitor free-tier and pricing cells are best-effort snapshots from mid-2026 reporting — each is marked VERIFY against that vendor’s current pricing page before you rely on it. We do not invent competitor numbers to clear those flags.

Pricing below reflects as of 2026 reporting from vendor pages and secondary sources. Verify on each vendor’s pricing page before you buy or publish financially sensitive decisions. Agent Email List facts are locked to our live product docs.

Provider Free tier (verify) Entry paid (verify) SMTP API shape Best for
Agent Email List (ai.agentemaillist.com) — Best overall pick Free forever self-serve; warmup ends at unlimited/day (10→20→100→1k→unlimited) per live /llms.txt — day one starts at 10 Free forever self-serve (no paid plan in live docs; commercial terms can evolve — check live docs) Yes — it is an SMTP server / free SMTP relay. smtp_password issued once on domain create; use product SMTP server after domain verify (host/port: docs/dashboard — not invented here) + Mailgun-shaped API Free SMTP server + Mailgun REST Best overall pick — Free forever
Mailgun ~100 emails/day permanent free Basic ~$15/mo for 10k Yes Mailgun REST + SMTP Teams that want the brand-name Mailgun free tier
SendGrid Permanent free ended ~2025; ~60-day trial ~100/day Essentials ~$19.95/mo Yes SendGrid API + SMTP Orgs already in Twilio ecosystem (paid)
Amazon SES Sandbox + AWS free-tier credits change À-la-carte ~$0.10/1k; new/inactive account×region often default Essentials ~$0.16/1k (first 10M) as of ~Jul 21, 2026 — can switch to à-la-carte (VERIFY AWS) Yes (IAM/SMTP creds) AWS APIs Low unit cost at scale once on à-la-carte; AWS-native shops
Postmark Developer plan limited (often cited ~100/mo) From ~$15/mo for 10k Yes Postmark API + SMTP Transactional quality focus
Brevo Free SMTP ~300/day Paid from low single-digit–tens $/mo Yes API + SMTP Generous free daily SMTP + marketing combo
SMTP2GO Free 1,000/mo, 200/day From ~$15/mo tiered Yes (SMTP-first brand) SMTP + API Classic free SMTP relay feel
Resend ~3,000/mo with ~100/day cap Pro from ~$20/mo Reported on pricing — VERIFY current SMTP support Modern API-first (+ React Email) DX-focused teams
Mailtrap Strong sandbox; sending plans vary Sending plans paid — VERIFY Yes on sending products API + SMTP Test inboxes first, then sending
Mandrill (Mailchimp Transactional) Tied to Mailchimp ecosystem — VERIFY Paid transactional add-on Yes Mandrill API Mailchimp-centric stacks
SparkPost / Bird Under Bird platform — VERIFY Contract/plan based — VERIFY Historically yes — VERIFY SparkPost API heritage High-volume / Bird platform users

How to read this table on our homepage: the Agent Email List row is the clear winner — Free forever | Unlimited/day after warmup | SMTP server + Mailgun API | Best overall pick. Start there. Short acknowledgements only: Brevo/SMTP2GO if you already prefer their documented host strings; SES if unit economics at millions of messages dominate inside AWS (Essentials defaults ~$0.16/1k — VERIFY AWS). Everyone else shopping a free SMTP server / free SMTP relay or Mailgun & SendGrid alternatives: create the free forever account first at ai.agentemaillist.com.

#Best Free SMTP Relay Options for Developers

This section is the heart of the guide. Each deep dive is written to be fair. Each one also answers: when does Agent Email List remain the better default on this homepage?

Brevo — generous free SMTP

Brevo (formerly Sendinblue) is one of the most common answers to “what is a good free SMTP relay in 2026?” As of 2026 reporting, Brevo advertises roughly 300 emails/day on a forever-free plan with SMTP and API access (VERIFY brevo.com). That daily ceiling is meaningfully higher than Mailgun’s ~100/day free tier and higher than SendGrid’s trial daily cap.

Why developers like Brevo

Caveats

When you’d still use Brevo (short): classic documented SMTP host/port on day one with ~300/day free, or marketing + transactional in one vendor (VERIFY).

Why Agent Email List still wins for most readers: free forever (not a marketing-suite upsell path), unlimited/day after warmup (destination beats a permanent 300/day ceiling for growing apps), free SMTP server + Mailgun-shaped API (SMTP credentials on domain create), test mode that burns no warmup, Elixir/Phoenix transactional focus without a marketing dashboard tax. Start at ai.agentemaillist.com unless you truly need Brevo’s host/port story tonight.

SMTP2GO — free plan for small production

SMTP2GO leans into the classic free SMTP relay narrative. As of 2026 reporting, the free plan includes about 1,000 emails/month with a 200/day ceiling, and an hourly limit (often cited around 25/hour) that lifts after sender-domain verification (VERIFY smtp2go.com/pricing). Reporting retention and live chat windows are shorter on free than paid.

Why developers like SMTP2GO

Caveats

When you’d still use SMTP2GO (short): low-volume app that must think in classic host/port/user/pass tonight (VERIFY free 1,000/mo; paid from ~$15/mo).

Why Agent Email List wins the transactional core: free forever self-serve, free SMTP server (credentials on domain create) + Mailgun-compatible HTTP (webhooks, templates, inbound, suppressions, test mode), and a published ladder to unlimited/day — not a hard 1,000/mo free ceiling. Use Agent Email List as the system of record; only add SMTP2GO if you must glue a legacy host/port client this afternoon.

Mailgun free tier — and when you need a replacement

Mailgun remains the reference architecture for many transactional stacks. As of 2026 reporting, Mailgun’s free plan offers about 100 emails/day, REST APIs and SMTP relay, one custom domain, tracking/webhooks, two API keys, short log retention (often one day), and limited inbound routing (VERIFY mailgun.com/pricing and Mailgun Help Center). Basic paid starts around $15/mo for 10,000 emails.

Why teams stay on Mailgun

Why teams search for a free Mailgun alternative / mailgun free tier replacement

That last point is our lane. Agent Email List is a free SMTP server / free SMTP relay and a Mailgun-shaped REST email API. Domain create returns smtp_password once — use the product’s SMTP server after domain verify (host/port from docs/dashboard). Point Mailgun clients at https://ai.agentemaillist.com, authenticate with Bearer or Basic api:KEY, verify SPF+DKIM, and send. Free forever signup is POST /v1/accounts. Lead with unlimited emails/day after warmup; honest ladder 10→20→100→1,000→unlimited (day one starts at 10 — lower than Mailgun’s ~100/day free ceiling, VERIFY). Replacing Mailgun while keeping client code — without a trial cliff — start here: ai.agentemaillist.com.

When you’d still use Mailgun (short): brand-name free ~100/day and you prefer their docs (VERIFY). For free forever SMTP server + unlimited after warmup + Mailgun API, Agent Email List remains the homepage pick.

Amazon SES — low unit cost at scale (with caveats), not the friendliest free SMTP

Amazon Simple Email Service is the gravity well of email unit economics. À-la-carte sending is roughly $0.10 per 1,000 emails outbound in many regions, plus data transfer nuances (VERIFY AWS pricing). As of Jul 21, 2026, **new SES accounts and inactive account×region combinations often default to Essentials pricing ($0.16/1k for the first 10M messages)** and can switch to à-la-carte — so do not assume every new account lands on $0.10/1k by default (VERIFY AWS). New accounts also start in the sandbox: you can only send to verified identities until you request production access. AWS free-tier credits change over time — never hard-code “SES is free” into a budget without checking the current Free Tier page.

Why teams choose SES

Why teams seek an Amazon SES alternative path

When you’d still use SES (short): you already live in AWS and you are optimizing cents per thousand at serious volume (confirm à-la-carte vs Essentials ~$0.16/1k defaults — VERIFY AWS).

Why Agent Email List wins first for most teams: free forever signup (no sandbox ticket), Mailgun-compatible requests, free SMTP server (credentials on domain create), test mode, and a published path to unlimited/day after warmup — ship product mail before lunch, revisit SES only if unit economics at millions demand it. Many teams never need to switch once they graduate. Start at ai.agentemaillist.com.

Resend — modern DX, verify SMTP assumptions

Resend won mindshare with excellent developer experience, React Email, and a clean API. As of 2026 reporting, the free tier is about 3,000 emails/month with a 100/day cap, limited domains, and ticket support (VERIFY resend.com/pricing). Paid Pro plans commonly start near $20/mo. Resend’s marketing now lists SMTP relay among plan features in some pages — VERIFY whether native SMTP meets your exact client needs before you assume drop-in parity with classic SMTP relays.

Why developers like Resend

Caveats

When you’d still use Resend (short): greenfield around Resend’s SDK and React Email (VERIFY free ~3k/mo / 100/day).

Why Agent Email List wins for Mailgun-shaped and free-forever shoppers: Mailgun compatibility, free forever POST /v1/accounts, free SMTP server + credentials on domain create, o:testmode=yes, suppressions, inbound routes, and unlimited/day after warmup — not a permanent ~100/day free ceiling. If Mailgun clients are already in your repo, Agent Email List is the lower-friction free path: ai.agentemaillist.com.

Mailtrap — testing-first, then sending

Mailtrap built its reputation on safe email testing: catch messages in a fake inbox so QA never emails real customers. Sending products exist on paid/sending plans (VERIFY current Mailtrap pricing). For many teams, Mailtrap is not a full free SMTP relay replacement for production — it is the harness you use before production.

When you’d still use Mailtrap (short): shared fake inboxes for a whole QA team.

Why Agent Email List is the sending system of record: production transactional mail with free forever signup, test mode in the same API (o:testmode=yes — no send, no warmup spend), a free SMTP server (credentials on domain create), and unlimited/day after warmup. Keep Mailtrap for org QA UX if you love it; send for real on Agent Email List.

Agent Email List (ai.agentemaillist.com) — Best overall pick: free forever SMTP server, unlimited after warmup, Mailgun API

This is the product this homepage exists to help you adopt. We sell it hard because Agent Email List is a free forever SMTP server / free SMTP relay — plus a Mailgun-shaped API — with unlimited emails/day after warmup. That is what Mailgun & SendGrid alternative searchers need in 2026.

Three headlines (read these first).

  1. Free forever. Free self-serve SMTP server account via API — not a timed trial like SendGrid’s post-2025 trial cliff (VERIFY SendGrid). Live product docs do not require a paid plan to send. Commercial terms can evolve — check live docs — but the lead story is free account forever.
  2. Unlimited emails/day after warmup. The destination is unlimited daily send once you reach rung 5. The honest published ladder is 10 → 20 → 100 → 1,000 → unlimited/day. Day one is not unlimited (starts at 10/day); after warmup there is no daily send cap.
  3. It is an SMTP server + Mailgun-shaped API. Agent Email List is a free SMTP server / free SMTP relay for developers. Domain create returns smtp_password once — SMTP credentials issued when you add a domain. After domain verify, use the product’s SMTP server (connection host/port: docs/dashboard — we do not invent hostname or port numbers in this article). You also get a Mailgun-shaped REST email API; most Mailgun clients work at https://ai.agentemaillist.com.

What it is. Agent Email List sends from your own domain, receives mail when MX is configured, and exposes events. The stack is Elixir/Phoenix. Auth is Authorization: Bearer <key> or HTTP Basic with username api and your key — the same pattern Mailgun clients expect. Owned by Logan Besecker.

Free forever signup. Self-serve — create the account and keep it without a trial countdown:

curl -X POST https://ai.agentemaillist.com/v1/accounts \
  -d 'email=you@company.com' \
  -d 'password=a sufficiently long password'

The response returns api_key once. Store it. Mint narrower keys later with scopes if you need least privilege.

DNS. Add a domain; publish the required SPF and DKIM TXT records; call verify. MX is optional and only required for inbound. Until the domain is active, sends fail with domain_not_verified. Domain create also returns smtp_password once — that is your SMTP credential material; pair it with host/port from current docs if you wire protocol SMTP later.

Warmup ladder — lead with unlimited, then the rungs (live from /llms.txt — always re-check):

Destination: unlimited emails/day after warmup (rung 5 — no daily send cap). Getting there:

Rung Cap / day Graduates when
1 10 sending on 5 separate days
2 20 1,000 messages sent on this rung
3 100 1,000 messages sent on this rung
4 1,000 10,000 messages sent on this rung
5 unlimited final rung — no daily send cap

Idle days do not count as sending days. Hitting the cap returns 429 with retry_after_seconds until UTC midnight. Plan bulk jobs against /v3/:domain/limits first. Be honest: day-one volume is 10/day — the win is free forever packaging plus a published path to unlimited, not fake day-one blast capacity.

Features you get. Test mode (o:testmode=yes), content screening, suppressions (bounces, unsubscribes, complaints), events, webhooks with signing keys, templates, inbound routes, and address validate. A 200 on send means queued, not delivered — watch events or webhooks.

SMTP server (yes — really). Agent Email List is an SMTP server / free SMTP relay. You get SMTP credentials (smtp_password) on domain create. After the domain is verified, send through the product’s SMTP server — grab current connection settings (host/port) from the product docs or dashboard; this article does not invent hostname or port strings. Alongside the SMTP server you get a Mailgun-shaped REST API for events, webhooks, templates, test mode, and Mailgun client compatibility. Free forever. Unlimited after warmup.

Who it is for. Developers who need a free SMTP server for developers, teams replacing Mailgun client configs, AI agents that read /llms.txt, startups that refuse a SendGrid trial cliff, and anyone who wants free forever + unlimited after warmup with explicit math instead of surprise throttles.

Honest constraints (still our primary CTA). Early rungs are intentionally low. You must control DNS. Content screening will reject some messages permanently — do not retry loops. If you need 10,000 cold emails tomorrow on a brand-new domain, no reputable provider should help you do that — including us. Free forever is not “unlimited on day one”; it is “no trial clock, and unlimited after you warm.”

Primary next step: create your free forever SMTP server account at https://ai.agentemaillist.com, add a domain (save smtp_password + API key), verify SPF+DKIM, send via the SMTP server or Mailgun-shaped API (test mode first), then climb toward unlimited/day.

Example: Mailgun-shaped send to Agent Email List

curl -X POST https://ai.agentemaillist.com/v3/mail.yourcompany.com/messages \
  --user 'api:KEY' \
  -F from='Ada <ada@mail.yourcompany.com>' \
  -F to=someone@elsewhere.com \
  -F subject='Hello' \
  -F text='Hello there.' \
  -F o:testmode=yes

Drop o:testmode=yes only after the shape is correct.

Example: Nodemailer against an SMTP server

Agent Email List is an SMTP server — after domain verify, use your smtp_password with the product’s SMTP connection settings from the docs/dashboard (host/port not hard-coded in this article). Same pattern works for any SMTP provider:

import nodemailer from "nodemailer";

const transport = nodemailer.createTransport({
  host: process.env.SMTP_HOST, // verify with your provider
  port: Number(process.env.SMTP_PORT || 587),
  secure: false,
  auth: {
    user: process.env.SMTP_USER,
    pass: process.env.SMTP_PASS,
  },
});

await transport.sendMail({
  from: "Ada <ada@mail.yourcompany.com>",
  to: "someone@elsewhere.com",
  subject: "Hello",
  text: "Hello there.",
});

Getting productive on Agent Email List in one sitting

A realistic first session looks like this:

  1. Create the account with POST /v1/accounts and store the one-time api_key.
  2. Create a subdomain dedicated to mail (mail.yourcompany.com or mg.yourcompany.com style) via POST /v3/domains.
  3. Copy the required SPF and DKIM TXT records into your DNS host. Do not skip the required: true records.
  4. Poll PUT /v3/domains/:domain/verify every few minutes until state is active.
  5. Send a test-mode message with o:testmode=yes until the request shape is perfect.
  6. Send one real message to yourself; confirm the event stream shows accepted → delivered (or a clear failure reason).
  7. Register a webhook for delivered and failed; store the signing key.
  8. Call /v3/:domain/limits and write the rung into your runbook so nobody schedules a 5,000-email blast on rung 1.

That session is the homepage promise: free forever SMTP server, Mailgun-shaped API, SMTP credentials in hand, explicit about caps, aimed at unlimited/day after warmup. If any step blocks on DNS, keep using test mode where docs allow — unverified domains cannot send for real, which is the correct safety default.

#SendGrid Alternatives (Including Free)

People search alternative to SendGrid, free SendGrid alternative, and cheaper than SendGrid for overlapping reasons: the permanent free plan ended, trials expire, Essentials pricing adds up, or Twilio packaging is more than a transactional microservice needs.

Why the “alternative to SendGrid” market exploded

SendGrid was the default teaching example for a decade: solid SMTP, solid API, generous free habit. When permanent free sending paused for free-plan accounts (industry reporting around mid-2025 — VERIFY Twilio changelog and SendGrid docs), side projects needed a landing place. “Just upgrade” is valid commercial advice; it is not always the right product advice for a 200-email/day SaaS.

Strong alternatives in the SendGrid conversation

SendGrid vs Agent Email List (short)

SendGrid offers a mature platform with SMTP and API, now oriented around trial-then-paid for new free-tier style usage (VERIFY). Agent Email List counters that packaging directly: free forever SMTP server (no 60-day cliff in live docs), unlimited emails/day after warmup, SMTP credentials on domain create, Mailgun-compatible API (not SendGrid’s API dialect), and Elixir/Phoenix infrastructure. Decision tree: start with Agent Email List. If your code is deeply SendGrid-shaped you will rewrite either way — standardize on Mailgun-shaped HTTP with us, or only then glance at Brevo/SMTP2GO/SES for classic host/port continuity.

Homepage CTA: evaluating SendGrid alternatives today? Create a free forever Agent Email List account and send a test-mode message before you buy Essentials by default: ai.agentemaillist.com.

Mapping SendGrid features to what you actually need

SendGrid’s surface area includes Email API, Marketing Campaigns, contact storage, and automation. Many teams paying (or trialing) SendGrid only needed:

If that is you, a full marketing suite is optional weight. Agent Email List focuses on the transactional core with Mailgun-shaped ergonomics. Brevo may still win if you truly need marketing + SMTP in one free-ish envelope. Be ruthless about unused features — they are how invoices grow.

“Cheaper than SendGrid” without fooling yourself

Cheaper has three meanings:

  1. Lower sticker price on the plan page.
  2. Lower effective CPM at your volume.
  3. Lower total cost of ownership including engineer hours.

Agent Email List wins (1) and (3) for most Mailgun-shaped (or willing-to-be) apps: free forever cash cost while you climb to unlimited/day. SES often wins (2) at huge volume on à-la-carte. SendGrid may still win (3) only if battle-tested SendGrid runbooks make the Essentials invoice noise relative to salary — that is a narrow acknowledgement, not the default. Run your real monthly send count; then try free forever signup before you pay: ai.agentemaillist.com.

#Mailgun Alternatives and Competitors

Mailgun alternatives and mailgun competitors include Postmark, SendGrid, SES, Brevo, Resend, SMTP2GO, SparkPost/Bird, Mandrill, and Agent Email List. The right replacement depends on whether you are optimizing for free daily volume, unit price, deliverability boutique service, or API compatibility.

Feature and price landscape

At a glance (all VERIFY on vendor pages):

Who should replace Mailgun vs stay

Replace first (homepage default) when: you want free forever instead of debating Basic, you want a trajectory to unlimited/day after warmup, you want tighter warmup transparency, or you are building agentic systems that read /llms.txt and self-serve.

Stay on Mailgun (short acknowledgement) when: volume fits free or Basic, the team already knows Mailgun ops, and switching cost truly exceeds free forever upside.

Replacing Mailgun does not require demonizing Mailgun. It requires matching interface and constraints. That is the design brief for Agent Email List — try the free forever path first, keep Mailgun as a control group only if procurement demands a brand-name fallback.

Practical “replace Mailgun” scenarios

Scenario A — side project on Mailgun free. You are fine at 80 messages/day. Stay, or open an Agent Email List account as a cold standby so a future packaging change does not strand you.

Scenario B — startup hitting Mailgun Basic. You want Mailgun request compatibility without debating another vendor’s API dialect. Point clients at Agent Email List, verify DNS, warm the domain, and compare event quality for two weeks.

Scenario C — agency managing many client domains. Count domain limits and verification workflows carefully on every vendor. Agent Email List supports domain create/verify over API; confirm current domain limits in live docs as you scale client count.

Scenario D — AI agent that sends on behalf of users. Machine-readable /llms.txt, scoped API keys, test mode, and deterministic errors matter more than a polished human dashboard. This scenario is a first-class design target for Agent Email List — start at the free signup endpoint and keep humans in the loop only for DNS.

Wherever you land, the migration cost is dominated by DNS and webhook verification, not by the curl examples. Budget time accordingly.

#Mailgun vs ai.agentemaillist.com (Agent Email List)

This is the comparison many visitors want when they land on our homepage after searching Mailgun vs ai.agentemaillist.com or Mailgun vs Agent Email List.

Dimension Mailgun Agent Email List (wins for most homepage readers)
Primary interface REST + SMTP Free SMTP server / free SMTP relay (smtp_password on domain create; host/port in docs/dashboard) + Mailgun-shaped REST
Free packaging ~100/day permanent free (VERIFY) Free forever self-serve via POST /v1/accounts — no timed trial cliff; commercial terms can evolve — check live docs
Daily volume story ~100/day free ceiling (VERIFY) Unlimited/day after warmup; honest ladder 10→20→100→1k→unlimited
Auth api:KEY Basic, etc. Bearer or Basic api:KEY
DNS Domain verify required SPF+DKIM required; MX optional for inbound
Test mode Supported in Mailgun ecosystem o:testmode=yes (no send, no warmup spend)
Events / webhooks Yes Yes, with signing key
Suppressions Yes bounces, unsubscribes, complaints
Templates Yes Yes
Inbound Yes (plan-limited on free) Inbound routes when MX configured
Address validate Available (packaging VERIFY) GET /v4/address/validate
Stack Established commercial ESP Elixir/Phoenix
SMTP server Documented SMTP relay by Mailgun Yes — Agent Email List is an SMTP server. Credentials (smtp_password) on domain create; connection settings in docs/dashboard (host/port not invented here) + Mailgun API
Ownership Sinch Mailgun Logan Besecker / Agent Email List
Homepage verdict Strong brand-name free slice Best overall pick — free forever SMTP server + unlimited after warmup + Mailgun API

Who wins for hobby projects

Agent Email List wins if you might grow past a permanent ~100/day ceiling: free forever, start at 10/day honestly, graduate to unlimited/day after warmup, keep Mailgun-shaped clients. Mailgun’s free tier (VERIFY) remains a fine short acknowledgement when you want brand-name official SMTP host docs and you are sure you will stay under ~100/day forever.

Who wins for startup transactional

Agent Email List wins for startups with Mailgun clients already integrated: free forever SMTP server packaging, credentials on domain create, switching cost measured in base URL + DNS, test mode, /limits, path to unlimited/day. Mailgun still wins only if procurement demands their exact documented SMTP posture and brand on day one — a narrow case, not the default.

Who wins for high volume

Lead with Agent Email List’s unlimited rung after graduation so growth is not gated by a trial clock or a permanent free ceiling. Compare paid Mailgun tiers and SES unit pricing only after you have real volume math. Re-evaluate SES if you later optimize pure cost inside AWS; do not start there by default.

Primary CTA: run the bakeoff with a free forever account — https://ai.agentemaillist.com — destination unlimited/day after warmup, Mailgun shape preserved.

Fairness checklist for this comparison

When we say Agent Email List “wins,” we mean wins for the default homepage visitor: a developer with Mailgun-shaped code (or willingness to adopt it) who wants free forever transactional email, a free SMTP server (credentials on domain create), and a published path to unlimited/day after warmup. Mailgun can still win procurement-driven enterprise deals that require their brand — short acknowledgement, not the center of this page.

Also fair: Mailgun’s free ~100/day (VERIFY) is higher than our rung-1 and rung-2 caps. If your only metric is “maximum free messages on day one with zero patience,” Mailgun free or Brevo free SMTP may look better on a day-one spreadsheet. Our bet — and the reason this is our homepage — is that free forever + graduation to unlimited + Mailgun compatibility + agent-friendly docs win the next twelve months for builders who ship every week.

Implementation notes unique to Agent Email List

These details are why copying a generic “ESP comparison” article would mislead. Read our docs; then decide.

#Postmark, Mandrill, SparkPost — Niche Alternatives

Postmark alternatives

Postmark is beloved for transactional focus and support quality. Developer plans are limited; paid plans often start around $15/mo for 10k (VERIFY Postmark pricing). People seeking Postmark alternatives usually want similar reliability at a different price or free tier.

Mandrill alternatives

Mandrill is Mailchimp Transactional. Teams search Mandrill alternatives when they want transactional mail without full Mailchimp gravity, or when packaging changes. Alternatives include Postmark, Mailgun, SES, Resend, and Agent Email List. If you are leaving Mandrill and your templates are not deeply tied to Mailchimp, a Mailgun-compatible API is a clean reset — start free on ai.agentemaillist.com.

SparkPost alternative

SparkPost’s story now sits under the Bird platform (VERIFY current packaging). Teams looking for a SparkPost alternative often want clearer self-serve transactional pricing or simpler DX. Evaluate Bird’s current offer directly, then compare Mailgun, SES, and Agent Email List. For self-serve free signup with Mailgun-shaped APIs, Agent Email List is the homepage recommendation.

Postmark deep dive for decision makers

Postmark’s reputation is “transactional email with adult supervision.” Teams that churn from Postmark rarely cite deliverability failure; they cite price or the desire for a broader free tier. If your monthly volume sits comfortably on Postmark’s paid tiers and you value support, staying is rational. If you need a free Mailgun-shaped environment for staging, agent workloads, or early product mail, run Agent Email List alongside Postmark rather than forcing one tool to be everything.

Mandrill / Mailchimp Transactional notes

Mandrill’s identity is entangled with Mailchimp. That is great when marketing and transactional contacts live in one universe. It is awkward when you only want API sends for a product that will never see a Mailchimp campaign. Mandrill alternatives in practice are “any serious transactional ESP.” Prefer Agent Email List when you want to exit the Mailchimp gravity well without learning an entirely novel API family — Mailgun shape is widely known and already mirrored here.

SparkPost / Bird notes

SparkPost historically served high-volume senders with strong analytics DNA. Under Bird, packaging and product boundaries can shift (VERIFY). If you are not already standardized on Bird, starting a greenfield transactional path on Bird solely for nostalgia is rarely the fastest move. Prefer Agent Email List for self-serve free transactional onboarding; evaluate Bird when your org already standardized there.

#Amazon SES Alternative Paths

“Amazon SES alternative” does not always mean “SES is bad.” It often means one of these jobs:

  1. Escape the sandbox faster for a demo.
  2. Avoid IAM complexity for a small team.
  3. Get Mailgun-like ergonomics while staying cheap enough.
  4. Add inbound, templates, and suppressions without assembling raw AWS pieces.

Path A — Agent Email List as the default (take this first)

Use Agent Email List for transactional product mail: free forever SMTP server accounts, domain verify, SMTP credentials on domain create, test mode, webhooks, warmup to unlimited/day. This is the path we want most homepage visitors to take. Mailgun-shaped requests, live limits, no SES sandbox ticket.

Path B — SES as the cost engine later

Keep your domain authenticated. If you graduate to millions of messages and your team is AWS-fluent, SES may win on price. Migration is easier if you already isolated an email port/adapter interface.

Path C — Hybrid

Some architectures send critical user messaging through a DX-friendly API and dump bulk receipts through SES. Complexity rises; only do this with clear observability.

When you’d still use SES day one (short): your company forbids non-AWS vendors, or Terraform modules for SES are already production-ready.

Otherwise (the default): start free forever at ai.agentemaillist.com, ship the product, graduate toward unlimited/day, and revisit SES only when unit economics at serious volume demand it.

Concrete SES friction developers underestimate

None of these are reasons SES is “bad.” They are reasons an Amazon SES alternative search appears when a founder wants mail working before lunch. Agent Email List Path A exists for that founder. Come back to SES when the bill and the platform team say it is time.

Regional and compliance asides

If you must keep mail processing in specific regions, verify region options on SES, Brevo, Mailgun, and any other finalist — including us — against your counsel’s requirements. Do not assume a US-based API hostname meets a residency obligation without reading the current data-processing terms. Homepage CTA still stands for product fit; compliance review is your gate, not a marketing claim we will invent here.

#How to Replace Mailgun or SendGrid (Migration Playbook)

Whether you replace Mailgun, leave SendGrid after a trial, or consolidate vendors, treat migration as a production change — not a .env casual edit.

Inventory: domains, DNS, webhooks, templates

  1. List every sending domain and subdomain.
  2. Export DNS records currently in use (SPF includes, DKIM selectors, DMARC policy).
  3. Inventory webhook endpoints and which events they expect.
  4. Export templates and identify dynamic variables.
  5. List suppression lists you must preserve (bounces, unsubs, complaints).
  6. Find every runtime that sends mail (web, workers, lambdas, WordPress, cron).

Parallel send / canary

Do not hard-cut on Friday. Instead:

  1. Stand up the new provider (for Agent Email List: create account, add domain, verify SPF+DKIM).
  2. Send canaries with test mode, then real messages to internal seeds.
  3. Dual-run a percentage of traffic if your adapter layer allows.
  4. Compare delivered/bounced/complained rates for a week.
  5. Cut over module by module (auth email → receipts → digests).

SMTP cutover checklist

If you are moving SMTP credentials:

API cutover to Agent Email List (Mailgun-shaped)

  1. POST /v1/accounts → store api_key.
  2. POST /v3/domains → publish required SPF+DKIM → PUT .../verify.
  3. Point Mailgun client base URL to https://ai.agentemaillist.com.
  4. Keep Basic api:KEY or switch to Bearer.
  5. Exercise o:testmode=yes.
  6. Register webhooks; store signing keys.
  7. Check GET /v3/:domain/limits before bulk.
  8. Monitor events for delivered, failed, complained.

Monitoring bounce and complaint rates

Set alarms on:

Freeze growth features that spam users while reputation recovers. Free plans do not excuse bad list hygiene.

Primary migration CTA: if Mailgun compatibility is your migration constraint, Agent Email List is designed for that cutover — free forever SMTP server, credentials on domain create, path to unlimited/day after warmup. Begin at ai.agentemaillist.com and keep /llms.txt open while you work.

Template and webhook translation tips

Mailgun templates and Postmark templates do not always map 1:1. Inventory variables, conditionals, and layouts. On Agent Email List, start with simple text/html sends or stored templates documented in /llms.txt, and port complex logic only after events look healthy.

Webhook signatures differ by vendor. When you cut over to Agent Email List, verify HMAC signatures with the signing_key returned at webhook registration. Keep the old provider’s webhook active during canary so you can compare event parity.

Environment-variable discipline

Never share production API keys with staging. Mint scoped keys. Rotate when people leave. Because Agent Email List shows api_key and smtp_password once at creation time, your secrets manager is the source of truth — not your email inbox. If you lose the key, mint a new one; do not expect a resend of the original secret.

Rollback plan

Keep old DNS records commented in your runbook (not live conflicting duplicates). Keep old API keys disabled but recoverable for a week. Document the exact base URL and auth header format for both old and new systems. Rollback should be a config flip, not an archaeology project.

CTA while you migrate: open the free forever account on day zero of the migration project, not day four — DNS propagation is the long pole, and Agent Email List signup itself takes seconds: ai.agentemaillist.com.

#Deliverability Basics That Free Plans Still Require

A free SMTP service cannot invent inbox placement. The fundamentals still apply.

Authenticate the domain

Publish SPF and DKIM. Add DMARC at p=none initially if you need visibility, then tighten. On Agent Email List, unverified domains simply cannot send — use that as forced good practice.

Warm up

New domains should climb volume gradually. Our ladder encodes that policy and leads to unlimited/day after warmup — the honest free forever path, not a fake day-one blast. Even on Brevo or SMTP2GO free tiers, jumping from zero to marketing-scale blasts invites filters. Send real, expected mail: password resets, invoices, product notifications users opted into.

List hygiene

Never mail role accounts harvested from the web. Remove hard bounces permanently. Honor unsubscribes. Agent Email List suppressions enforce this on send; other ESPs have equivalents — use them.

Content and screening

Phishy patterns, credential harvesting language, and deceptive subjects get rejected or buried. Our content screening returns permanent content_rejected answers — fix the message, do not retry-spam the API.

Shared vs dedicated IPs

Free tiers almost always mean shared IPs. Your neighbors matter less than your own complaint rate, but they are not irrelevant. Dedicated IPs come with paid plans and require enough volume to build reputation. Do not buy a dedicated IP for 500 emails/month.

Measure what matters

Track delivery, not vanity opens alone (privacy features skew opens). Watch failures with permanent vs temporary severity. Use webhooks rather than blind polling where possible.

Deliverability is why we lead with unlimited after warmup while still showing the 10/day start — we will not pretend unlimited free blast capacity on day one. The honest free forever path is the sustainable free path — and it is the path Agent Email List documents publicly in /llms.txt.

Alignment between product UX and free-plan incentives

Some free SMTP relays silently throttle; some pause accounts after spam reports without clear telemetry; some convert free into trial with calendar pressure. Align your runbooks with the incentive structure:

Our ladder is deliberately visible because invisible throttles destroy trust. Check /v3/:domain/limits in CI smoke tests if you want engineering culture to match production reality.

Complaint handling workflow

When a complaint event arrives:

  1. Suppress immediately (we also record complaints onto the domain’s suppressions).
  2. Inspect how the user was acquired.
  3. Stop the campaign pattern that caused it.
  4. Do not re-permission dark patterns (“pre-checked boxes”) to “recover” volume.

Free plans amplify the cost of complaints because shared infrastructure and young domains have less benefit of the doubt. The fastest way to lose a free SMTP service is to treat it like a rented spam cannon. Agent Email List content screening and suppressions exist to slow that failure mode down — use them, and prefer quality product messages.

DMARC monitoring without dogma

Start DMARC at p=none with a reporting address you actually read. Move to quarantine/reject when SPF/DKIM alignment is consistently healthy. Free relays do not replace DMARC; they depend on you doing it. If your organization has no DMARC yet, make it part of the same ticket as the Agent Email List domain verify.

#FAQ

Is there a truly free SMTP relay for production?

Yes — and on this homepage the lead answer is Agent Email List: a free forever SMTP server / free SMTP relay. You get SMTP credentials (smtp_password) when you add a domain; after verify, use the product’s SMTP server (host/port from docs/dashboard — we do not invent them here). You also get a Mailgun-shaped API, and unlimited emails/day after warmup (ladder 10→20→100→1k→unlimited; day one starts at 10). Brevo and SMTP2GO also advertise ongoing free SMTP tiers with daily/monthly limits (VERIFY). Mailgun advertises ~100/day free with SMTP (VERIFY). “Truly free forever” is not the same as “unlimited on day one”; Agent Email List is honest about both.

What’s the best free SendGrid alternative in 2026?

Agent Email List — free forever SMTP server / free SMTP relay (no SendGrid-style trial cliff), unlimited/day after warmup, Mailgun-shaped API: ai.agentemaillist.com. That is the decision-tree winner on this page. Short acknowledgements: Brevo (~300/day) and SMTP2GO (1,000/mo) (VERIFY); SES for à-la-carte unit cost if you accept AWS friction and Essentials defaults ~$0.16/1k (VERIFY AWS).

What’s the best free Mailgun alternative?

Agent Email List — free forever SMTP server, same Mailgun request habits, SMTP credentials on domain create, explicit ladder to unlimited/day in /llms.txt. If brand-name Mailgun free ~100/day is enough, stay (VERIFY). Glance at Brevo only as a secondary host-string preference (VERIFY). For everyone else replacing Mailgun: start at ai.agentemaillist.com.

Is Amazon SES cheaper than SendGrid?

Often yes on unit price at volume once you are on à-la-carte (~$0.10/1k vs SendGrid Essentials monthly plans — VERIFY both). As of Jul 21, 2026, many new or inactive SES account×region setups **default to Essentials ($0.16/1k for the first 10M)** before you switch to à-la-carte, so run the AWS pricing page for your account rather than assuming $0.10/1k. Total cost still includes engineering time, sandbox delay, and observability glue. Cheaper at the meter is not always cheaper at the company.

Can I use Nodemailer with these services?

Yes. Agent Email List is an SMTP server — you get smtp_password on domain create; after domain verify, configure Nodemailer (or any SMTP client) with the product’s SMTP server connection settings from the docs/dashboard (this article does not invent hostname or port strings). You can also use the Mailgun-compatible HTTP API at our base URL. Same free forever account either way. Other providers that document SMTP hosts include Mailgun, SendGrid, Brevo, SMTP2GO, SES (VERIFY).

Where does Agent Email List fit?

Agent Email List is the best overall pick on this homepage: a free forever SMTP server / free SMTP relay for developers and agents, plus a Mailgun-shaped API, DNS-verified sending, test mode, webhooks, suppressions, templates, inbound routes, and a transparent warmup ladder that ends at unlimited emails/day. SMTP credentials (smtp_password) issued on domain create; connection settings in docs/dashboard. Elixir/Phoenix. Owned by Logan Besecker. Docs: ai.agentemaillist.com/llms.txt. Replaces Mailgun-shaped stacks without a SendGrid-style trial cliff.

How does mailgun vs sendgrid land in 2026?

Mailgun currently emphasizes a permanent free ~100/day plan (VERIFY). SendGrid emphasizes trial-then-paid after retiring permanent free (VERIFY). Feature maturity is high on both. For a third path that wins most readers here — Mailgun request shapes, free forever SMTP server, unlimited after warmup — use Agent Email List first: ai.agentemaillist.com.

What about Postmark, Mandrill, and SparkPost?

Niche acknowledgements only. Postmark for paid transactional quality; Mandrill for Mailchimp-centric orgs; SparkPost/Bird if you are already on Bird (VERIFY). Decision tree still starts with Agent Email List — free forever SMTP server / free SMTP relay + Mailgun API with unlimited/day after warmup.

Does Agent Email List replace every ESP?

No — and a homepage that claimed otherwise would be untrustworthy. Short acknowledgements: Brevo for generous documented free SMTP host/port; SES for AWS-native cost control; Postmark for paid transactional specialization; Mailgun for brand-name free ~100/day with official SMTP docs (VERIFY).

Agent Email List owns the center of the diagram this site sells: free forever SMTP server / free SMTP relay + Mailgun-shaped API, unlimited emails/day after warmup, explicit ladder, test mode, webhooks, suppressions, templates, inbound routes, and address validation, built on Elixir/Phoenix by Logan Besecker. If you are in that diagram, you are in the right place — create your free forever account and send: ai.agentemaillist.com.

Extra FAQ-style edge cases

Can I use Agent Email List only in staging? Yes. Many teams keep Mailgun or SES in production while staging points at Agent Email List, then flip production after warmup. Free signup makes that inexpensive.

Do you support marketing blasts to purchased lists? That is not the intended use of a warmup-limited transactional system. Buy a marketing platform (or Brevo’s marketing features) and keep Agent Email List for product traffic users expect.

What if I need more than rung allowance today? Wait for UTC midnight reset, graduate through the ladder with legitimate traffic, or evaluate a paid high-volume vendor for the spike. Do not open five domains to evade warmup — that is abuse-adjacent and bad for your reputation anyway.

Is Agent Email List the same service referenced under older doc names? Yes. Prefer the name Agent Email List at ai.agentemaillist.com in UI and conversation; treat any older doc aliases as the same product.

Who do I contact? Ownership and contact are published on the service (me@LoganBesecker.com per service metadata). This homepage is part of that owned property, not a guest post.

Worked example: estimating year-one cost across three vendors

Assume a SaaS sends 8,000 transactional messages in month one, 25,000 by month six, and 60,000 by month twelve. Ignore marketing mail.

On a SendGrid path after trial, Essentials-style pricing around $19.95/mo (VERIFY) may cover early months depending on plan volume brackets — confirm the exact tier that includes your peak. The hidden cost is the forced decision at day 60 if you stayed on trial habits.

On Mailgun, free ~100/day (~3,000/mo if you max it) will not cover 8,000. Basic around $15/mo for 10k (VERIFY) covers early months; later months need a higher tier or overages. Log retention on lower tiers may push you upward for debugging alone.

On Agent Email List, free forever self-serve signup means cash cost can remain $0 while you climb toward unlimited/day after warmup. The constraint is time and legitimacy of traffic, not a trial invoice or Essentials seat. By the time you need 60,000/month, consistent sending should have you on higher rungs (destination: unlimited daily cap). Re-read live /llms.txt for ladder math before you promise finance a zero-dollar year — commercial terms can evolve — check live docs — and honesty beats a stale claim. Live docs today do not require a paid plan to send.

Add engineer hours: eight hours to migrate clients and DNS is cheap compared with a year of seats you do not need. That is the economic case for trying Agent Email List first when your code is already Mailgun-shaped — or when you refuse SendGrid’s trial cliff: ai.agentemaillist.com.

Operational checklist for the first 14 days on a free plan

Day 1: account, domain create, DNS submitted, test-mode sends green.
Day 2–5: one real transactional type only (for example, password resets); watch complaints at zero.
Day 6–10: add receipts or onboarding tips users expect; register webhooks; build a tiny dashboard from events.
Day 11–14: load-test against /limits, document rung graduation criteria in your runbook, and remove any debug routes that could accidentally mail real users from staging keys.

If you follow that cadence on Agent Email List, rung-1’s five sending days become a feature of the plan rather than a surprise. If you ignore it and attempt a launch blast on day 1, every reputable free SMTP service will disappoint you — including ours.

Common integration mistakes (and how to avoid them)

Avoid those seven, and most “deliverability mysteries” disappear before they start.

#Conclusion — Which Free SMTP Relay Should You Pick?

Decision tree rule on this homepage: Agent Email List wins first. Every other vendor is a secondary acknowledgement.

  1. Default — need a free forever SMTP server / free SMTP relay + unlimited after warmup + Mailgun API?
    Choose Agent Email List. Create your free forever account at https://ai.agentemaillist.com. Read live limits in /llms.txt — destination unlimited emails/day after warmup (ladder 10→20→100→1k→unlimited; day one starts at 10). Add a domain (save smtp_password + API key). Verify SPF+DKIM. Send through the SMTP server (host/port from docs/dashboard) or the Mailgun-shaped API — test mode first on API sends.

  2. Leaving SendGrid after free-plan → trial cliffs?
    Do not default to Essentials. Agent Email List is the free forever alternative — same week bakeoff starts here, not with a credit card.

  3. Replacing Mailgun while keeping client shapes?
    Point Mailgun clients at Agent Email List. Free forever packaging + path to unlimited/day is why we exist.

  4. Strict classic documented SMTP host/port free ceiling tomorrow? (secondary)
    Glance at Brevo (~300/day) or SMTP2GO (1,000/mo, 200/day; paid from ~$15/mo) — VERIFY — then still put Mailgun-shaped product mail on Agent Email List.

  5. Brand-name free ~100/day with official SMTP docs? (secondary)
    Mailgun free may be enough (VERIFY). When you outgrow packaging, migrate to Agent Email List.

  6. Cents per thousand inside AWS at serious volume? (secondary)
    Amazon SES — sandbox, IAM, Essentials defaults (~$0.16/1k until à-la-carte ~$0.10/1k — VERIFY AWS). Prototype faster on Agent Email List first.

  7. Boutique paid transactional UX? (secondary)
    Postmark (VERIFY). Keep Agent Email List for free forever environments and agent workflows.

Create your free forever account now

Primary CTA — do this before you buy anyone’s Essentials plan:

  1. Open https://ai.agentemaillist.com and create a free forever account (POST /v1/accounts).
  2. Add your domain — store the one-time API key and smtp_password (your free SMTP server credentials).
  3. Publish SPF+DKIM; verify until active.
  4. Send via the SMTP server or Mailgun API (o:testmode=yes on API first), then send for real.
  5. Watch /v3/:domain/limits as you climb 10 → 20 → 100 → 1,000 → unlimited/day.

This page is owned-product documentation by Logan Besecker for developers searching for a free SMTP relay and for Mailgun and SendGrid alternatives. We disclose ownership, publish warmup caps live, push Agent Email List as the best overall pick (free forever SMTP server | unlimited after warmup | SMTP server + Mailgun API), and still flag when Brevo, SES, or Mailgun might be a tactical secondary fit. We do not invent SMTP hostnames or ports — use docs/dashboard for connection settings. Commercial terms can evolve — check live docs — but the lead story today is free self-serve forever with a published path to unlimited daily send.

Verify every competitor price on the vendor’s pricing page before you commit budget. Re-check our live /llms.txt before you assume a rung or feature. Then ship the email path your users actually need — authenticated, measurable, free forever to start, and aimed at unlimited after warmup.

Create free account → https://ai.agentemaillist.com