A Beta version of LISTSERV has a DBMS feature.  Current and older
production versions have the standard feature called TOPICS.

Some long-time subscribers of LSTOWN-L will recognize my previous post:


It takes 3 things to accomplish your task via LISTSERV(R) technology:

1) list-owner has setup the list's TOPICS feature in the
   definition (see example below)

2) you, the subscriber, have done a LISTSERV

   SET listname TOPICS: -FWD

   which only is effective for mail distributions, and not
   for DIGEST/INDEX mailings

3) the sender uses a valid Subject: in their posting

   SUBJECT: FWD: xxxxxxx

Here is an example syntax using HEPROC-L topics=

* Topics=          HEJ,Con1,Con2,Con3,Con4,Con5,Con6,Con7,Con8,Con9

Notice that there is nothing magical about FWD and is not a valid
explicit topic for this list (thus it would be treated as the
reserved OTHER: topic).