You can include extra information in your mail address. This extra information is referred to as "subaddress". Any material following a plus, +, in your address is considered to be a subaddress. For instance, "test" in the address bob+test@example.com is a subaddress.

A subaddress in a PMDF MessageStore address is considered to describe the folder to which the message should be delivered. For instance, for the PMDF MessageStore user bob@example.com, a message addressed to bob+test@example.com would be delivered to bob's folder named "test".