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Please read the Postfix documentation on virtual aliases first.

You can use instead of creating and editing files manually. Aliases are managed in /tmp/docker-mailserver/ An alias is a full email address that will either be:

  • delivered to an existing account registered in /tmp/docker-mailserver/
  • redirected to one or more other email addresses

Alias and target are space separated. An example on a server with as its domain:

# Alias delivered to an existing account

# Alias forwarded to an external email address

Configuring RegExp Aliases

Additional regexp aliases can be configured by placing them into docker-data/dms/config/ The regexp aliases get evaluated after the virtual aliases (container path: /tmp/docker-mailserver/ For example, the following docker-data/dms/config/ causes all email sent to "test" users to be delivered to instead:


Address Tags (Extension Delimiters) an Alternative to Aliases

Postfix supports so-called address tags, in the form of plus (+) tags - i.e. will end up at This is configured by default and the (configurable !) separator is set to +. For more info, see the official documentation.


If you do decide to change the configurable separator, you must add the same line to both docker-data/dms/config/ and docker-data/dms/config/, because Dovecot is acting as the delivery agent. For example, to switch to -, add:

recipient_delimiter = -