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.
Growth work lives or dies on targeting and measurement. What matters is whether behavioral triggers can be built without engineering time, whether the event stream supports attribution past the open, and whether deliverability holds when broadcast volume shares a reputation with product email.
Against behavior-triggered journeys, broadcasts, and winback campaigns measured on revenue, MailCatcher covers none of the capabilities this audience leans on (scheduling, event stream, the suppressions API, and multi-tenant support), so it fits only where those needs are genuinely absent.
- Scheduling: No
- Event stream: No
- Deliverability: Not applicable.
- Operating since: Not published
- Suppressions API: No
- Best published rate per 1,000: Tiers not published in comparable form
- Multi-tenant: No
- Free tier: Free, MIT-licensed
- Starts at: Free
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 |