Postmark vs Mailgun
Transactional deliverability specialist versus flexible developer email infrastructure.
What matters for SaaS product teams
A SaaS product sends on behalf of its customers, so the deciding factors are tenant isolation, whether suppressions can be scoped rather than global, and whether support can answer why one specific account did not receive one specific email. Lifecycle automation and transactional sending usually need to coexist.
| Priority | Postmark | Mailgun |
|---|---|---|
| Multi-tenant | Yes | Yes |
| Event stream | Yes | Yes |
| Suppressions API | Yes | Yes |
| Operating since | 2010 | 2010 |
| Scheduling | No | Yes |
| Best published rate per 1,000 | $1.50 | $0.70 |
| Deliverability | Strong transactional reputation with separate streams for transactional and broadcast traffic, which helps protect sender reputation. | Generally good, with deliverability monitoring tools available on higher tiers. Inbound routes and suppressions are battle-tested. |
| Webhooks | Yes | Yes |
| Starts at | $15/mo for 10,000 emails | $15/mo for 10,000 emails (Basic) |
For a multi-tenant SaaS product running trial expiry notices, dunning, onboarding sequences, and per-tenant transactional mail, Mailgun takes every priority that separates them here (scheduling and best published rate per 1,000), while Postmark matches it on the rest. On entry price, Postmark offers $15/mo for 10,000 emails against $15/mo for 10,000 emails (Basic) from Mailgun. That ordering reflects this audience. Weigh the same table differently and the answer changes.
Side by side
| Feature | Postmark | Mailgun |
|---|---|---|
| Multi-tenant | Yes | Yes |
| Deliverability | Strong transactional reputation with separate streams for transactional and broadcast traffic, which helps protect sender reputation. | Generally good, with deliverability monitoring tools available on higher tiers. Inbound routes and suppressions are battle-tested. |
| Webhooks | Yes | Yes |
| Starts at | $15/mo for 10,000 emails | $15/mo for 10,000 emails (Basic) |
| Tagline | Transactional-only, fast and well-delivered. | Developer-leaning email infra, owned by Sinch. |
| Free tier | 100/mo developer plan | 100/day permanent free plan |
| Pricing model | tiered | tiered |
| API | Yes | Yes |
| SMTP | Yes | Yes |
| SDKs | node, python, go, ruby, php, java, elixir, rust, dotnet | node, python, go, ruby, php, java |
| Templates | rich | rich |
| React Email | No | No |
| Inbound | Yes | Yes |
| Idempotency | No | No |
| Dedicated IP | Yes | Yes |
| DX score | 9/10 | 7/10 |
| Best for | Teams where password resets, receipts, and magic links absolutely cannot miss the inbox. | Technical teams that want SMTP relay plus advanced routing. |
Postmark
- ›Transactional-only routing and strong operational history
- ›Streams cleanly separate transactional and broadcast
- ›Free DMARC monitoring product (dmarc.postmarkapp.com)
- ›Retains full message content and metadata for 45 days for debugging
- ›No idempotency keys
- ›Pricing per email is higher than SES, Mailgun, or SMTP2GO
- ›No drag-and-drop template builder
- ›Marketing automation is intentionally absent
Mailgun
- ›Strong SMTP relay support, useful when migrating off self-hosted Postfix
- ›Inbound routes with regex matching
- ›Validation and parsing tools available
- ›Sub-accounts for agency use cases
- ›Overage pricing and plan differences need close review at scale
- ›Documentation is comprehensive but occasionally out of date
- ›No idempotency keys
- ›Sinch ownership has moved focus toward enterprise