Warming up
Every account now comes with a free mailbox — warmed automatically, no domain to buy. See how it works
Transactional email API
Every account now comes with a free mailbox — warmed automatically, no domain to buy. See how it works
Choose Mailgun if you send 50,000 to 100,000 a month and want the lower list price and a free plan you can use daily; choose Postmark if you want the longest message history and a service built only for transactional mail. On list prices as of September 2026: at 10,000 both list at $15; at 50,000 Mailgun lists lower ($35 against $55); at 100,000 Mailgun lists lower ($90 against $115). The 500,000 row is left open because a plan at that size is not priced here. Prices are the cheapest published monthly plan that covers each volume, with overage left out.
What each one lists for the same monthly volume, from their own pricing pages.
| Emails a month | Mailgun | Postmark | Warmerly |
|---|---|---|---|
| 10,000 | $15Basic 10k | $15Basic 10k | $15Starter |
| 50,000 | $35Foundation 50k | $55Basic 50k | $15Starter |
| 100,000 | $90Scale 100k | $115Basic 125k | $29Growth |
| 500,000 | see vendor site | $455Basic 700k | $279Scale 500k |
List prices, monthly billing, USD: the cheapest published plan that includes that many emails, overage left out. Prices from mailgun.com and postmarkapp.com as of September 2026; check their sites for current rates. Shaded cells are the cheaper of the two; Warmerly is shown for reference.
What each one does today. Warmerly is a third option for API-only app email; where it says "not yet", it means it.
| Feature | Mailgun | Postmark | Warmerly |
|---|---|---|---|
| API shape | REST, form-encoded POST to /v3/{domain}/messages, HTTP Basic auth with your API key | REST, POST /email with PascalCase fields; server token header | REST, JSON over HTTPS, bearer key, Idempotency-Key header |
| SMTP relay | Yes | Yes | Not yet (on the roadmap) |
| Delivery webhooks | Yes | Yes | Not yet. Read each email's delivery timeline from GET /emails/{id} |
| Templates | Yes, from the Foundation plan | Yes | Not yet. You send your own HTML and text |
| Dedicated IP | One included on Scale; $59/mo for each extra IP | From $50/mo, for 300,000+ emails a month on Pro or higher | $29/mo on Scale plans |
| Suppression list | Bounces, complaints and unsubscribes are suppressed automatically | Automatic on hard bounce and spam complaint, per message stream | Automatic on hard bounce and spam complaint, shared with Warmerly outreach |
| Free tier | 100 emails a day, with 1 day of logs | 100 emails a month | 5,000 a month (200 a day), no time limit, no card |
| Log retention | 1 day on Free and Basic, 5 on Foundation, 30 on Scale | 45 days; up to 365 on Pro and Platform (add-on from $5/mo) | Content 30 days; the email record and its delivery events are kept |
| SDKs | Official libraries for several languages (see mailgun.com) | Official libraries for several languages (see postmarkapp.com) | None. One HTTP request from any language |
| Support | See mailgun.com | See postmarkapp.com | Email (support@warmerly.com), plus a 99.9% monthly uptime commitment with service credits |
Neither is right for everyone. These are the cases that decide it.
Warmerly sends through Amazon SES and keeps transactional mail apart from cold outreach. It has a free plan of 5,000 emails a month, but it is REST only today: no SMTP relay, delivery webhooks or templates yet. If an API is all you need, see how it compares on the Mailgun alternative and Postmark alternative pages.
On list prices as of September 2026: at 10,000 both list at $15; at 50,000 Mailgun lists lower ($35 against $55); at 100,000 Mailgun lists lower ($90 against $115). The 500,000 row is left open because a plan at that size is not priced here. Overage rates and plans larger than those compared are not included, so check each vendor's pricing page for your exact volume.
Mailgun: 100 emails a day, with 1 day of logs. Postmark: 100 emails a month.
Mailgun: Yes. Postmark: Yes.
Mailgun: 1 day on Free and Basic, 5 on Foundation, 30 on Scale. Postmark: 45 days; up to 365 on Pro and Platform (add-on from $5/mo).
Warmerly is a transactional email API that sends through Amazon SES. It lists $15 a month for 50,000 emails and a free plan of 5,000 emails a month, but it is REST only and has no SMTP relay, webhooks or templates yet. Compare it on the Mailgun alternative and Postmark alternative pages.
Create a free account, verify a sending domain and send a test from the dashboard. 5,000 emails a month free, no card.
