MailCatcher
Tiny Ruby-based local SMTP catcher.
MailCatcher is a Ruby gem that runs a local SMTP server on port 1025 and a web UI on 1080. It is common in Rails projects and shows the HTML, plain-text, and raw-source version of each captured message. Development is slow, so Mailpit is usually the stronger default today.
Judged purely as an API. What the request contract guarantees on retry, how complete the webhook event coverage is, whether suppressions are readable and writable programmatically, and how much the message log retains when something needs debugging in production.
Against high-frequency programmatic sends where a missed delivery is a product failure, MailCatcher covers none of the capabilities this audience leans on (idempotency keys, webhook coverage, event stream, the suppressions API, batch sending, and SDK breadth), so it fits only where those needs are genuinely absent.
- Idempotency keys: No
- Webhooks: No
- Event stream: No
- Operating since: Not published
- Suppressions API: No
- Best published rate per 1,000: Tiers not published in comparable form
- Batch sending: No
- SDKs: None
- Deliverability: Not applicable.
Not applicable.
Rails teams already running it in development.
Non-Ruby projects, which get a lighter setup from Mailpit.
- › Installs as a Ruby gem, familiar in Rails stacks
- › SMTP on 1025 with a web UI and JSON API on 1080
- › Shows HTML, plain text, and raw source per message
- › Release cadence is slow with little active feature work
- › Needs a Ruby runtime where Mailpit ships a static binary
- › HTML rendering trails newer catchers
Features at a glance
| API | Yes |
| SMTP | Yes |
| SDKs | None |
| Webhooks | No |
| Templates | none |
| React Email | No |
| Batch send | No |
| Scheduled send | No |
| Suppressions | No |
| Multi-tenant | No |
| Inbound parsing | No |
| Event stream | No |
| Idempotency keys | No |
| Dedicated IP | No |