If you enter a subaddress into your personal alias database as
    a public alias, then you can have mail sent to you with that
    subaddress automatically forwarded. For example, suppose that
    your address is bob@example.com and mail to you from the STAFF
    mailing list arrives addressed to bob+staff@example.com. If
    you create a public alias for staff then mail to the address
    bob+staff@example.com will be forwarded to the address associated
    with the alias. For instance, the commands

    db> add staff bob+staff@naples.example.com
    db> set staff public

    cause mail sent to bob+staff@example.com to be forwarded to
    bob+staff@naples.example.com.