head to head
Mailpit vs MailDev
Two local SMTP catchers: a single Go binary against an npm install that suits Node projects.
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 | Mailpit | MailDev |
|---|---|---|
| Inbound parsing | No | No |
| Idempotency keys | No | No |
| Webhooks | No | Yes |
| Operating since | Not published | Not published |
| Event stream | No | No |
| Best published rate per 1,000 | Tiers not published in comparable form | Tiers not published in comparable form |
| Batch sending | No | No |
| SDKs | None | None |
| Multi-tenant | No | No |
For an agent that reads and writes email running inbound parsing into tool calls and model-generated sends that must not duplicate, MailDev takes every priority that separates them here (webhook coverage), while Mailpit matches it on the rest. That ordering reflects this audience. Weigh the same table differently and the answer changes.
Side by side
| Feature | Mailpit | MailDev |
|---|---|---|
| Webhooks | No | Yes |
| SDKs | None | None |
| Multi-tenant | No | No |
| Tagline | Modern local SMTP catcher. | Node-based local SMTP catcher. |
| Free tier | Free, MIT-licensed | Free |
| Starts at | Free | Free |
| Pricing model | self-hosted | self-hosted |
| API | Yes | Yes |
| SMTP | Yes | Yes |
| Templates | none | none |
| React Email | No | No |
| Inbound | No | No |
| Idempotency | No | No |
| Dedicated IP | No | No |
| Deliverability | Not applicable; capture-only. | Not applicable. |
| DX score | 9/10 | 6/10 |
| Best for | Replacing MailHog in any local or CI email-capture setup. | Node-centric local development and CI. |
Mailpit
pros
- ›Single Go binary or small Docker image with no runtime dependencies
- ›Reuses MailHog's 1025 and 8025 ports, so most existing configs work unchanged
- ›Views for rendered HTML, plain text, raw source, headers, and attachments
- ›Built-in HTML-compatibility check, link check, and spam-score view
- ›REST API and real-time inbox updates for automated tests
cons
- ›Local development and staging only, not a production sender
- ›No hosted or shared team-inbox mode
MailDev
pros
- ›Installs with a single npm install or docker run
- ›SMTP on 1025 with a web UI and REST API on 1080
- ›Optional webhook on new mail for CI assertions
- ›Relay mode can forward caught mail to a real SMTP host
cons
- ›Vue UI renders modern HTML email less faithfully than Mailpit
- ›Release cadence is slower than Mailpit