You would like to use the address to identify the assignee.
This is not specific to directives, nor does it require your mailbox to support many addressees as per 'Project Auto Assign', though if it can, it will be used.
Example Test Case Message
This message can be cut/pasted into a JEMH Test Case.
Received: by 10.223.112.12 with HTTP; Tue, 4 Dec 2012 22:42:26 -0700 (PDT)
Date: Tue, 4 Dec 2012 17:42:26 +1200
Subject: This is a starting email template, update as required
From: "A User" <firstname.lastname@example.org>
Content-Type: text/plain; charset=UTF-8
Project Auto Assign from Sub-Address
If checked will be used to locate a match in the to: address, in the example above, the addressee is:
This will be broken into groups by regular expression: (admin)+(test)(@localhost) and result in the following:
The first capture group 'admin' will be looked up, and if a valid user, will be set as the assignee. Note that the validity of this user to be used as the assignee is not checked at this point, as the project has not yet been determined.
The second capture group 'test' will be looked up during project selection processing, equally, if valid, will be used.
If you have Catch Email Addresses configured, they must be updated to include a Regular Expression that matches your inbound address. The following expression would match andy.brook+helpdesk@localhost: