Postfix SMTP only with relay support

Postfix SMTP only Docker image with SMTP relay support.

Rocky Linux: 9.3
Postfix: 3.5.9
Expose: 25

Supported tags and respective Dockerfile links

Important

Starting with the release 3.5-1.0, the MTP_USER and MTP_PASS variables became mandatory, as without them, emails are rejected as SPAM and are not sent

:latest Dockerfile - Rocky Linux: 9.3 Postfix: 3.5.9
:3.5-1.0 Dockerfile - Rocky Linux: 9.3 Postfix: 3.5.9
:2.10-3.8 Dockerfile - CentOS: 7 Postfix: 2.10.1

See older versions

Base docker image

hub.docker.com

Source code

github.com

Usage

Start postfix (to send emails using postfix within container)

$ docker run --rm --name=postfix \
             -e  MTP_HOST=foo.com \
         eeacms/postfix

or start postfix (to send emails by using a remote email server)

$ docker run --rm --name=postfix \
             -e MTP_HOST=foo.com \
             -e MTP_RELAY=smtp.gmail.com \
             -e MTP_USER=foo \
             -e MTP_PASS=secret \
         eeacms/postfix

Start sending emails:

$ docker run -it --rm --link=postfix busybox sh
  $ telnet postfix 25
  HELO foo.com
  MAIL FROM: bar@foo.com
  RCPT TO: foo@bar.com
  DATA
  subject: Test
  Testing 1, 2, 3
  .
  quit

Supported environment variables

MTP_HOST The myhostname parameter specifies the internet hostname of this mail system
MTP_DESTINATION The mydestination parameter specifies the list of domains that this machine considers itself the final destination for.
MTP_BANNER The smtpd_banner parameter specifies the text that follows the 220 code in the SMTP server's greeting banner.
MTP_RELAY The relayhost parameter specifies the default host to send mail to when no entry is matched in the optional transport(5) table.
MTP_RELAY_DOMAINS The relay_domains parameter restricts what destinations this system will relay mail to.
MTP_PORT The relayhost port.
MTP_USER The user used to connect to the relayhost.
MTP_PASS The password used to connect to the relayhost.
MTP_INTERFACES The inet_interfaces parameter specifies the network interface addresses that this mail system receives mail on.
MTP_PROTOCOLS The inet_protocols parameter specifies the network interface protocol. Can be set to all, ipv4,ipv6 or ipv4,ipv6. The default value is all.
MTP_MS_SIZE_LIMIT If set, will configure email size limit.
SMTPD_TLS_SECURITY_LEVEL The SMTP TLS security level for the Postfix SMTP server. Default value: none. Possible values: none(TLS will not be used), may( Opportunistic TLS), encrypt(Mandatory TLS encryption)
SMTP_TLS_SECURITY_LEVEL The default SMTP TLS security level for the Postfix SMTP client. Default value: may. Possible values: none(TLS will not be used), may( Opportunistic TLS), encrypt(Mandatory TLS encryption)

Copyright and license

The Original Code is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

Funding

European Environment Agency (EU)

eea/eea.docker.postfix