MailHog
Classic local SMTP catcher (unmaintained since 2020).
MailHog popularized the local SMTP-catcher pattern. It is written in Go, runs SMTP on 1025 and a web UI on 8025, and shipped with a "Jim" chaos-testing mode. The repository has seen no meaningful updates since 2020. Mailpit is a drop-in replacement on the same ports.
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.
Against inbound parsing into tool calls and model-generated sends that must not duplicate, MailHog covers none of the capabilities this audience leans on (inbound parsing, idempotency keys, webhook coverage, event stream, batch sending, SDK breadth, and multi-tenant support), so it fits only where those needs are genuinely absent.
- Inbound parsing: No
- Idempotency keys: No
- Webhooks: No
- Operating since: Not published
- Event stream: No
- Best published rate per 1,000: Tiers not published in comparable form
- Batch sending: No
- SDKs: None
- Multi-tenant: No
Not applicable; capture-only.
Legacy projects already wired to it.
New projects. Mailpit runs on the same ports with active maintenance.
- › Familiar from years of tutorials and boilerplates
- › Single Go binary with a Docker image and a chaos-testing mode
- › No meaningful releases since 2020
- › HTML and modern CSS rendering trails current email clients
- › Open issues and pull requests are effectively unattended
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 |