jeeva420/exim4-smtp repository overview

⁠Quick reference

This image allows linked containers to send outgoing email. You can configure it to send email directly to recipients, or to act as a smart host that relays mail to an intermediate server (eg, GMail, SendGrid).

• Reference: https://github.com/BytemarkHosting/docker-smtp⁠

⁠Usage

⁠Basic SMTP server

In this example, linked containers can connect to hostname mail and port 25 to send outgoing email. The SMTP container sends email out directly.

docker run --restart always --name mail -d jeeva420/exim4-smtp

⁠Via Docker Compose:

version: '3.9'
services
  mail:
    image: jeeva420/exim4-smtp
    restart: always

⁠SMTP smart host

In this example, linked containers can connect to hostname mail and port 25 to send outgoing email. The SMTP container acts as a smart host and relays mail to an intermediate server server (eg, GMail, SendGrid).

docker run --restart always --name mail \
    -e RELAY_HOST=smtp.example.com \
    -e RELAY_PORT=587 \
    -e [email protected] \
    -e RELAY_PASSWORD=secretpassword \
    -d jeeva420/exim4-smtp

⁠Via Docker Compose:

version: '3.9'
services:
  mail:
    image: jeeva420/exim4-smtp
    restart: always
    environment:
      RELAY_HOST: smtp.example.com
      RELAY_PORT: 587
      RELAY_USERNAME: [email protected]
      RELAY_PASSWORD: secretpassword

⁠Environment variables

All environment variables are optional. But if you specify a RELAY_HOST, then you'll want to also specify the port, username and password otherwise it's unlikely to work!

• MAILNAME: Sets Exim's primary_hostname, which defaults to the hostname of the server.
• RELAY_HOST: The remote SMTP server address to use.
• RELAY_PORT: The remote SMTP server port to use.
• RELAY_USERNAME: The username to authenticate with the remote SMTP server.
• RELAY_PASSWORD: The password to authenticate with the remote SMTP server.
• RELAY_NETS: Declare which networks can use the smart host, separated by semi-colons. By default, this is set to 10.0.0.0/8;172.16.0.0/12;192.168.0.0/16, which provides a thin layer of protection in case port 25 is accidentally exposed to the public internet (which would make your SMTP container an open relay).