head to head
Resend vs Mailgun
Modern React-oriented API versus mature SMTP, routing, and high-volume tooling.
What matters for teams building autonomous agents
An agent stack treats email as a two-way primitive. Inbound has to arrive as structured JSON a tool call can consume, sends have to be safe to retry when a model loop repeats itself, and every action needs an audit trail. A provider without inbound parsing only solves half the problem.
| Priority | Resend | Mailgun |
|---|---|---|
| Inbound parsing | Yes | Yes |
| Idempotency keys | Yes | No |
| Webhooks | Yes | Yes |
| Operating since | 2023 | 2010 |
| Event stream | Yes | Yes |
| Best published rate per 1,000 | $0.35 | $0.70 |
| Batch sending | Yes | Yes |
| SDKs | node, python, go, ruby, php, rust, java, elixir, cli | node, python, go, ruby, php, java |
| Multi-tenant | No | Yes |
For an agent that reads and writes email running inbound parsing into tool calls and model-generated sends that must not duplicate, Resend takes idempotency keys, best published rate per 1,000, and SDK breadth, while Mailgun takes operating track record and multi-tenant support. That ordering reflects this audience. Weigh the same table differently and the answer changes.
Side by side
| Feature | Resend | Mailgun |
|---|---|---|
| Webhooks | Yes | Yes |
| SDKs | node, python, go, ruby, php, rust, java, elixir, cli | node, python, go, ruby, php, java |
| Multi-tenant | No | Yes |
| Tagline | Email API tightly coupled to React Email. | Developer-leaning email infra, owned by Sinch. |
| Free tier | 3,000/mo permanent, capped at 100/day, one domain | 100/day permanent free plan |
| Starts at | $20/mo for 50,000 emails | $15/mo for 10,000 emails (Basic) |
| Pricing model | tiered | tiered |
| API | Yes | Yes |
| SMTP | Yes | Yes |
| Templates | react-email | rich |
| React Email | Yes | No |
| Inbound | Yes | Yes |
| Idempotency | Yes | No |
| Dedicated IP | Yes | Yes |
| Deliverability | Acceptable, but the deliverability track record is shorter than Postmark or SendGrid. Independent inbox-placement studies vary. Dedicated IPs are available on higher tiers. | Generally good, with deliverability monitoring tools available on higher tiers. Inbound routes and suppressions are battle-tested. |
| DX score | 8/10 | 7/10 |
| Best for | Early-stage React or Next.js product teams sending under 50k/mo. | Technical teams that want SMTP relay plus advanced routing. |
Resend
pros
- ›Idiomatic SDKs across major languages
- ›React Email integration is the smoothest of any provider
- ›Idempotency keys supported
- ›Clean dashboard and event log
cons
- ›Volume pricing is significantly higher than AWS SES at large volumes
- ›Founded 2023, so deliverability track record and incident history are still building
- ›No drag-and-drop template editor; non-React stacks get a thinner experience
- ›Free tier is capped at 100 sends a day, so a 3,000/mo allowance cannot absorb a launch spike
- ›January 2024 breach exposed email metadata, contacts, and encrypted API tokens for all users; message bodies were not reached
- ›Status page logged roughly ten incidents in the three weeks to 2026-08-01, mostly outside the sending path: dashboard, webhooks, domain verification, and automations
- ›Single-region historically; multi-region setup is newer
- ›Smaller support footprint than Twilio SendGrid or Sinch Mailgun
Mailgun
pros
- ›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
cons
- ›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