Cuttlefish
Open-source transactional email server with a web UI.
Cuttlefish is a self-hosted transactional email server with SMTP delivery, bounce handling, open and click tracking, real-time analytics, a web UI, and an API. It runs on top of Postfix and is explicitly positioned as free and open source software.
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, Cuttlefish covers event stream and multi-tenant support, and does not cover inbound parsing, idempotency keys, webhook coverage, batch sending, and SDK breadth. Whether that gap matters depends on how central those are to the build.
- Inbound parsing: No
- Idempotency keys: No
- Webhooks: No
- Operating since: Not published
- Event stream: Yes
- Best published rate per 1,000: Tiers not published in comparable form
- Batch sending: No
- SDKs: None
- Multi-tenant: Yes
Self-hosted deliverability depends on Postfix configuration, IP reputation, DNS authentication, bounce processing, and list hygiene. Cuttlefish adds bounce suppression and analytics around SMTP delivery.
Teams that want a self-hosted transactional email dashboard in front of Postfix.
Teams that need managed deliverability, inbound parsing, or template tooling.
- › Open-source transactional email with a useful web UI
- › SMTP integration works with any framework or language
- › Bounce handling, open tracking, click tracking, and application-level analytics are built in
- › Project site describes the product as beta
- › Official site says it does not handle incoming email or built-in templates
- › Requires Postfix and self-hosted operations expertise
Features at a glance
| API | Yes |
| SMTP | Yes |
| SDKs | None |
| Webhooks | No |
| Templates | none |
| React Email | No |
| Batch send | No |
| Scheduled send | No |
| Suppressions | Yes |
| Multi-tenant | Yes |
| Inbound parsing | No |
| Event stream | Yes |
| Idempotency keys | No |
| Dedicated IP | No |