The only solution I can think of is either a gateway system that receives
the messages and replaces the dash with a colon, or then the use of a
DISTRIBUTE job to bypass this nonsense. I realize neither is practical,
but then there are always going to be mail systems where users don't have
full control over their subject field. For instance, I know mail systems
that translate "Re:" to the local language before sending. LISTSERV can't
possibly know about all the national variants of "Re:", and won't detect
the topic properly in this case either. There are also a lot of mail
systems where the subject is always "INTER OFFICE MEMORANDUM" or
equivalent, no matter what the user types. Some categories of users just
don't have access to their subject field when sending outside the
organization.
Eric