FastSMTP

A TLS-capable, async SMTP server that receives email, verifies DKIM and SPF, and forwards the contents to configurable webhooks. Built for Python 3.12+ and for integration with n8n and other webhook-based workflow platforms.

This is the server package. The remote CLI client is a separate distribution, fastsmtp-cli, which talks to a running server over HTTP and does not depend on this one.

Install

pip install fastsmtp

On Alpine and other musl-based distributions, note that google-re2 publishes manylinux wheels but no musllinux wheels, so pip has to build it: install a compiler and the RE2 library first, or use the container image instead.

Container images are published to ghcr.io/jsenecal/fastsmtp.

Run

export FASTSMTP_DATABASE_URL=postgresql+asyncpg://user:pass@localhost/fastsmtp
export FASTSMTP_ROOT_API_KEY=$(python -c "import secrets; print(secrets.token_urlsafe(32))")

fastsmtp db upgrade head   # apply migrations first, every time
fastsmtp serve

Configuration is read from FASTSMTP_* environment variables and from a .env file in the working directory. Migrations are never applied automatically: run fastsmtp db upgrade head before starting a newer version, or the server refuses to start against a database behind it.

Documentation

Full documentation, including the configuration reference, the HTTP API and the rules engine, is at https://jsenecal.github.io/fastsmtp/.

Source and issue tracker: https://github.com/jsenecal/fastsmtp.

License

AGPL-3.0-or-later - this program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. See LICENSE.