Subaddresses

   Subaddresses provide a convenient handle for screening e-mail
   messages with DELIVER.

   To screen mail based upon a subaddress, you must use a 1, 2,
   or 3 action to obtain the envelope TO: address associated with
   the mail message being delivered to you. You cannot use headers
   since there is no requirement that your address has to appear in
   the header of messages you receive, either with or without the
   subaddress. For instance, to detect the subaddress "junk-mail",
   use the directives

   *  *             * T 2 "ENVELOPE-TO"
   * "*+junk-mail*" * T D WASTEBASKET

   The first of these two directives tells DELIVER to use the
   envelope TO: address for 2-PATTERN. The second directive then
   causes any messages with +junk-mail appearing in the envelope TO:
   address to be filed to your WASTEBASKET folder.