You can use [`setup.sh`][docs-setupsh] instead of creating and editing files manually. Aliases are managed in `/tmp/docker-mailserver/postfix-virtual.cf`. An alias is a _full_ email address that will either be:
Additional regexp aliases can be configured by placing them into `config/postfix-regexp.cf`. The regexp aliases get evaluated after the virtual aliases (`/tmp/docker-mailserver/postfix-virtual.cf`). For example, the following `config/postfix-regexp.cf` causes all email to "test" users to be delivered to `qa@example.com`:
Postfix supports so-called address tags, in the form of plus (+) tags - i.e. address+tag@example.com will end up at address@example.com. This is configured by default and the (configurable !) separator is set to `+`. For more info, see [How to use Address Tagging (`user+tag@example.com`) with Postfix](https://www.stevejenkins.com/blog/2011/03/how-to-use-address-tagging-usertagexample-com-with-postfix/) and the [official documentation](http://www.postfix.org/postconf.5.html#recipient_delimiter).
If you do decide to change the configurable separator, you must add the same line to *both*`config/postfix-main.cf` and `config/dovecot.cf`, because Dovecot is acting as the delivery agent. For example, to switch to `-`, add: