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Table of contents

  1. frontline
  2. auth
  3. forwarding
  4. maildb
  5. mailout

Components architecture overview

The Mailway email service is divided into multiple components:


The frontline service is exposing the public email and HTTPS server. It’s NGINX compiled with the email module.

Sources on GitHub: frontline.


When NGINX starts to receive an email, the auth service will be called to authenticate the communication and select a SMTP server that will receive the email.

Sources on GitHub: auth.


The forwarding component has the main business logic, which includes:

  • applying the routing rules
  • dropping or forwarding the email
  • calling webhooks
  • spam filtering

Sources on GitHub: forwarding.


For logging and debugging purposes, the email’s metadata (to, from, time, etc) will be recorded into a database, namely the maildb service.

The service exposes a public API via the frontline (protected by JWT tokens) that allow the dashboard to query the logs.

Sources on GitHub: maildb.


Emails that need to be sent to another email server after being processed will be sent to the mailout service.

mailout will attempt to send the email from the current server, however the target email server might reject the email (due to IP reputation for example). As a fallback the email will be sent to another smtp server. See Alternative out SMTP.

Sources on GitHub: mailout.