Postmark vs Mailgun
Transactional deliverability specialist versus flexible developer email infrastructure.
What matters for early-stage startups
At an early stage the deciding factors are what the free tier actually covers, what the first paid invoice looks like, and how much of a founding engineer's week the setup costs. Feature depth that only matters at a million sends a month is noise until it is not.
| Priority | Postmark | Mailgun |
|---|---|---|
| Free tier | 100/mo developer plan | 100/day permanent free plan |
| Best published rate per 1,000 | $1.50 | $0.70 |
| Starts at | $15/mo for 10,000 emails | $15/mo for 10,000 emails (Basic) |
| DX score | 9/10 | 7/10 |
| 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. |
| Operating since | 2010 | 2010 |
| Scheduling | No | Yes |
| SDKs | node, python, go, ruby, php, java, elixir, rust, dotnet | node, python, go, ruby, php, java |
| Webhooks | Yes | Yes |
For a pre-revenue or early-revenue team running a waitlist, a launch announcement, onboarding email, and the first transactional sends, the split is even: Postmark takes developer experience and SDK breadth, Mailgun takes best published rate per 1,000 and scheduling. Neither pulls ahead on this audience's priorities. On free tier, Postmark offers 100/mo developer plan against 100/day permanent free plan from Mailgun. That ordering reflects this audience. Weigh the same table differently and the answer changes.
Side by side
| Feature | Postmark | Mailgun |
|---|---|---|
| Free tier | 100/mo developer plan | 100/day permanent free plan |
| Starts at | $15/mo for 10,000 emails | $15/mo for 10,000 emails (Basic) |
| DX score | 9/10 | 7/10 |
| 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. |
| SDKs | node, python, go, ruby, php, java, elixir, rust, dotnet | node, python, go, ruby, php, java |
| Webhooks | Yes | Yes |
| Tagline | Transactional-only, fast and well-delivered. | Developer-leaning email infra, owned by Sinch. |
| Pricing model | tiered | tiered |
| API | Yes | Yes |
| SMTP | Yes | Yes |
| Templates | rich | rich |
| React Email | No | No |
| Inbound | Yes | Yes |
| Multi-tenant | Yes | Yes |
| Idempotency | No | No |
| Dedicated IP | Yes | Yes |
| 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