Transactional email APIs · Comparison
Resend vs Postmark vs Mailgun: Resend leads at 8.2, with 50,000 emails for $20
We read the pricing, security and docs pages of three transactional email APIs on the same day and scored them on the same six indicators. What each one sells, what 50,000 emails cost, and who should pick which.
On this page8 sections
On six indicators read from each vendor's public pages, Resend scores 8.2, Mailgun 7.5 and Postmark 5.8 out of 10. Resend lists the lowest price at 50,000 emails a month ($20) and puts its SOC 2 Type II report and a pre-signed DPA on every plan. Mailgun has the fullest compliance and access package: its own SOC 2 Type II and ISO 27001, US or EU sending, and SAML SSO at $90. Postmark scores lowest on this rubric, mainly on price at 50,000 emails ($66 by its listed overage) and because the SOC 2 report it offers is its data center's. It is also the only one of the three with inbound email processing and up to 365 days of message history.
The scores measure what the public pages commit to. They do not measure deliverability, speed or how a product feels to use, and we did not sign up for any of the three.
At a glance
| Resend | Postmark | Mailgun | |
|---|---|---|---|
| What you pay for | Compliance documents on every plan, at a low price | Inbound processing and long message history | Own certifications, EU sending, SSO at $90 |
| Free tier | 3,000/mo, 100 a day | 100/mo (for testing) | 100 a day, 1 user |
| Price at 50,000 emails/mo | $20 (Pro) | $66–$87, computed from listed overage | $35 (Foundation) |
| SOC 2 | Type II, self-serve download | Data center's, under NDA | Type II, plus ISO 27001 |
| EU option | EU sending region; data stored in the US | No; US hosting | US or EU sending region |
| SSO | $150/mo add-on on Scale | Not listed | SAML on Scale ($90) |
| Retention on the entry paid plan | 30 days | 45 days (up to 365 on Pro) | 1 day of logs (Basic) |
| Score (public pages) | 8.2 Excellent | 5.8 Fair | 7.5 Good |
What the public pages show
Resend prices transactional email by emails sent; marketing email is a separate plan priced by contacts. Its security page is direct: the SOC 2 Type II report and a DPA executed at sign-up are downloads under Settings → Documents on every plan, and it states that Resend is not HIPAA compliant, cannot sign a BAA and stores data in the United States even when you pick an EU sending region. The docs offer 14 quickstarts, from Node.js to Rust, Elixir and .NET.
Postmark sells paid plans that each include 10,000 emails a month, then overage. The pricing page says "No Credit Card Required" and frames the free Developer plan as a test plan of 100 emails a month. Inbound processing and retention up to 365 days start on Pro; unlimited users and domains come with Platform. Its EU privacy page is candid: Postmark has not had its own SOC audit; its data center has, and that report is available under NDA. Data is hosted in the US, with no EU servers planned.
Mailgun, part of Sinch, runs from a free tier of 100 emails a day to Scale at $90 for 100,000 a month; Foundation and Scale start with a one-month free trial. The security page lists SOC 2 Type II and ISO/IEC 27001 for Mailgun itself, plus two-factor and SAML authentication, and the docs describe US and EU domains in one control panel.
Strengths and things to know
Resend. Strengths: compliance documents on the free plan, the lowest listed price at 50,000 emails, clear statements of its limits. Things to know: no HIPAA BAA, stored data stays in the US, the free plan caps at 100 emails a day, and SSO is a $150/mo add-on.
Postmark. Strengths: no card to start, inbound email on Pro and Platform, history up to 365 days, unlimited users and domains on the $18 Platform plan, no daily cap on paid plans. Things to know: no SOC 2 report of its own, US hosting only, and above 10,000 emails you pay overage or ask sales.
Mailgun. Strengths: two certifications of its own, an EU sending region, SAML SSO with phone support at $90, unlimited users from Foundation. Things to know: logs are kept 1 day on Free and Basic and 5 on Foundation, and the pricing table and FAQ describe dedicated IP inclusion differently, so ask before counting on one.
Pricing reality
All three price by emails sent. At 50,000 a month:
| Service | Plan | Monthly cost | Where the number comes from |
|---|---|---|---|
| Resend | Pro | $20 | Listed: 50,000 included |
| Mailgun | Foundation | $35 | Listed: 50,000 included, after a one-month free trial |
| Postmark | Platform | $66 | Computed: $18 for 10,000, plus 40,000 at $1.20 per 1,000 |
Postmark does not list a 50,000-email price, so its figure is our arithmetic from the overage it publishes. The 40,000 emails beyond each plan's 10,000 make $87 on Basic ($1.80 per 1,000), $68.50 on Pro ($1.30) or $66 on Platform ($1.20). High-volume senders are invited to ask sales for custom pricing; we did not ask.
Resend's Pro is $35 for 100,000 and its Scale runs to $1,150 for 2.5 million, with overage falling to $0.46 per 1,000. Mailgun's Scale is $90 for 100,000, then $1.10 per 1,000. Add-ons: Resend charges $30/mo for a dedicated IP and $150/mo for SSO; Postmark's dedicated IPs start at $50/mo for senders above 300,000 a month; Mailgun's extra dedicated IPs are $59 each per month.
How we scored them
Every product in this category is scored on the same six indicators, read from the vendor's own pricing, security or docs pages, with fixed formulas. The overall score is the plain mean. Our methodology page explains how these scores work.
| Indicator | Resend | Postmark | Mailgun |
|---|---|---|---|
| Pricing clarity | 10 | 7 | 9 |
| Free tier | 10 | 5.8 | 9 |
| Price at 50,000 emails | 10 | 4.1 | 7.2 |
| Compliance documents | 6.5 | 3 | 8 |
| Team access controls | 2.5 | 5 | 10 |
| Message history | 10 | 10 | 2 |
| Overall | 8.2 | 5.8 | 7.5 |
Postmark loses points on pricing clarity because volumes above its listed tier go through sales, and on compliance because the SOC 2 report is its data center's. Mailgun loses a point for the dedicated-IP statements that do not match, and most of its history score because Basic keeps one day of logs. Resend's lowest item is team access: SSO is an add-on, and its pages state neither a plan with unlimited users nor two-factor authentication.
The rubric rewards what a buyer can confirm before signing up. It has no item for inbound processing, Postmark's clearest difference, and it cannot see deliverability, support quality or how the API feels in daily use. Hands-on runs will add that evidence later.
Who should choose which
- Choose Resend if you want SOC 2 and DPA documents on any plan and the lowest listed price up to about 100,000 emails a month. Look elsewhere if you need a HIPAA BAA or EU data storage.
- Choose Mailgun if customers ask for ISO 27001, you need an EU sending region, or you want SAML SSO without an enterprise contract.
- Choose Postmark if you need to parse inbound email, keep history for up to a year, or start without a card. Check whether your security reviews accept a data-center SOC report.
Bottom line
From public pages alone, Resend is the cheapest way here to send 50,000 emails a month and the easiest to clear a security review with, and Mailgun is the most complete compliance package. Postmark is the pick when inbound email and long history matter more than price at volume; its lower score reflects what this rubric counts and says nothing about how well it delivers mail.
How we checked
We read the vendors' pricing, security or privacy, and documentation pages on Oct 15, 2026. We did not sign up, call an API or send email. Facts the pages did not state, such as whether Resend and Mailgun ask for a card, are left out rather than guessed. Every figure is on the vendors' pages as of that date or, for Postmark at 50,000 emails, computed from them as shown.
