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Transactional email API and SMTP

Postmark

A transactional-first email API and SMTP service that keeps bulk mail on separate message streams and retains 45 days of full message history.

Visit postmarkapp.com ↗ Alternatives Free tier
§1

Overview

Postmark is an email delivery service built around transactional mail: sign-up confirmations, password resets, receipts and alerts. You send through a REST API or SMTP, and bulk or marketing mail must go through separate Broadcast message streams so it cannot drag down the reputation of your transactional traffic.

Every paid plan includes 10,000 emails a month. Basic ($15) is the cheapest but has the highest overage rate ($1.80 per 1,000) and no inbound processing. Pro ($16.50) and Platform ($18) add inbound email, more domains and users, longer optional retention and cheaper overage. Since August 2025 those features are available at the 10,000 level instead of only on larger volume plans.

Full message content is kept for 45 days by default, which makes debugging a missing email easier than on services that keep only a few days of logs. The free Developer plan is limited to 100 emails a month with no overages, so it is for testing rather than running a small app.

Dedicated IPs are only offered to senders above 300,000 emails a month on Pro or higher. There is no EU data region and no annual billing.

§2

Pricing and plans

checked 28 Sept 2026

Free tier · no card

Developer plan: 100 emails a month, no overages, never expires

Plan Price What you get
Free $0/mo 100 emails/month, no overages
Basic $15/mo 10,000 emails, extra $1.80/1,000, 5 domains, 4 users, no inbound
Pro $16.50/mo 10,000 emails, extra $1.30/1,000, 10 domains, inbound, retention up to 365 days
Platform $18/mo 10,000 emails, extra $1.20/1,000, unlimited domains, servers and users
High volume Custom Contact sales for volumes above the slider

Prices shown are for the 10,000-email level; larger volume tiers are set with a slider on the pricing page that did not render for us, so costAt beyond 10,000 is left empty. Overage is billed on the next invoice. Add-ons: dedicated IP from $50/mo, custom retention from $5/mo, DMARC monitoring from $14/mo per domain. Bootstrapped companies can ask for $75 credit. No annual plans.

Source: postmarkapp.com/pricing · prices as published, excluding tax.

§3

What it does

Message streams
Transactional and broadcast mail travel on separate streams and infrastructure, up to 15, 30 or unlimited streams by plan.
Inbound processing
Incoming email is parsed into JSON and posted to your webhook. Included on Pro and Platform.
45-day message history
Full content and events are kept 45 days by default, customizable from 7 to 365 days as a paid add-on.
Templates
Responsive templates for common transactional emails plus a template editor and import tool.
Sandbox mode and webhooks
Test sends without delivery, and receive delivery, bounce, spam and open events on secured webhooks.
DMARC monitoring
Optional DMARC digests from $14/mo per domain to find authentication problems.
§4

Strengths and limitations

Strengths

  • Transactional and bulk mail are kept on separate streams by design
  • 45 days of full message content retained on every plan
  • Inbound email parsing available from $16.50/mo
  • Delivery statistics are published on the status page

Limitations

  • Free plan is only 100 emails a month with no overages
  • No tier between 100 and 10,000 emails a month
  • Dedicated IPs require 300,000+ emails a month
  • No annual plans and no PayPal or purchase orders
  • Unused emails do not roll over
§5

Who it suits

Good for

  • SaaS products where password resets and receipts are critical
  • Teams that need long message logs for support
  • Apps that also send some broadcast mail but want it isolated

Look elsewhere if

  • Hobby projects that need more than 100 free emails a month
  • Very high-volume senders optimizing purely for price
§6

Pricing history

  • Postmark Pro and Platform features available at 10,000 emails

    Announced and effective August 6, 2025: Pro and Platform features (inbound, more users and streams) became available at the 10,000-email level for $16.50 and $18 a month, instead of requiring larger plans previously priced at $60.50 and $138. Basic stayed at $15. Source ↗

§7

Alternatives to Postmark

Tool From Free option Stages
AhaSend Transactional email API and SMTP relay
$10/mo Free tier
Amazon SES Cloud email sending and receiving service
Usage-based Paid
Azure Communication Services Email Cloud email sending API
Usage-based Paid
Bento Email marketing and automation
$29/mo Paid
Brevo Email marketing and transactional platform
$9/mo Free tier
Emailit Email API and SMTP with prepaid credits
Usage-based Paid

Resend vs Postmark → All transactional email apis →

§8

Questions

Does Postmark have a free plan?

Yes. The Developer plan gives 100 emails a month for as long as you need, but it does not allow overages.

How much does Postmark cost for 10,000 emails?

$15 a month on Basic, $16.50 on Pro or $18 on Platform, each including 10,000 emails.

Can I send marketing email through Postmark?

Yes, but it must go through a Broadcast message stream, which is kept separate from transactional sending.

Does Postmark support inbound email?

Yes, on Pro and Platform plans. Incoming messages are converted to JSON and posted to a webhook.

Does Postmark offer dedicated IPs?

Yes, from $50 a month per IP, but only for senders of 300,000 or more emails a month on Pro or higher.

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