Dockerized Mailserver

Exposed Ports

Port	Service	Description
25	SMTP	Requires no authentication but is under heavy restrictions regarding the senders that are accepted based on spam protection heuristics
26	SMTP	Same as above but expects a PROXY-Protocol header
587	Submission	Mail submission port for users. Basically SMTP but STARTTLS as well as authentication are always required
993	Imap	Used for retrieving mails and managing mailboxes
4190	sieve-manage	Management port for sieve-scripts
11334	rspamd	HTTP server of the rspamd admin interface

Persistence

This container requires persistent volumes at the following locations:

• /app/mail for storing actual emails in maildir format
• /app/data for various database e.g. spam filter learnings

Config Files

• /app/conf/dovecot_local.conf A dovecot configuration file that is automatically included at the end of the container's configuration. This file must contain at least one passdb block so that dovecot knows how to authenticate users.

  • Dovecot Documentation Reference
  • Dovecot passdb Reference

• /app/conf/postfix_local.cf A postfix main.cf file that is automatically appended to the container's configuration.

  • Postfix Documentation Reference
  • All main.cf parameters

• /app/conf/postfix_virtual_alias_maps.txt A berkeley db table which lists email address aliases (Postfix reference).

  This basically means one alias per line in a <from> <to> format. These aliases can be recursive.

  For mails to be correctly deliverable, all aliases should finally resolve to a keycloak username.

• /app/conf/postfix_virtual_domains.txt A berkeley db table which lists domains for which this server accepts mails.

  The right-hand side of the table is completely ignored and can be anything.

• /app/conf/postfix_sender_login_maps.txt A lookup table that specifies which user is allowed to send from which address.

  Postfix Documentation

• /app/conf/postfix_recipient_access.txt A lookup table from which postfix determines specific actions that it performs depending on the resolved recipient address.

  Postfix Documentation

• /app/conf/rspamd_worker_controller.inc Incrementally applied configuration file for rspamd.

  It should at least set the following parameters:

  password = "$2$z4y5epzqj6jxzrkxca4wb4tszfnhmtcs$39tgkjx95srtw4mu9ey5fcxrn6yq4wsqy5z4eqxwijzbas9kq7wb";
  

• /app/conf/opendkim_domains.txt A file listing the domains which will be dkim signed.

• /app/conf/opendkim_key.pem The private key with which dkim signatures will be made.

• /app/ssl/tls.crt and /app/ssl/tls.key for TLS encryption.

• /app/conf/fetchmailrc for configuring fetchmail. See the documentation for the syntax of this file.

  Delivery options can be ignored in the config file as they are set as command line arguments to fetchmail by the container (see the launch script for details).

  The file could for example look like this:

  poll imap.mydomain.de protocol IMAP auth password
    user "ftsell" with password "…" is "ftsell" here