I set the Subject-Tag to the listname, but the listname still does not appear on the subject line of the messages
"Setting this keyword does not automatically reset users to the SUBJecthdr option. This must be done manually for existing users and may be specified by default for new subscribers by use of Default-Options=SUBJecthdr in the list header settings...
LISTSERV - Mailing List Service
July 5, 2016