Odds are, the other list is configured with "Language=NoHTML", which
causes LISTSERV to strip attachments which have a MIME type of
"text/html". Some list owners do this to reduce the risk of spreading
malicious HTML, some do it because they believe that HTML should be
used in web pages, not email, and some do it simply because the site
administrator configured the list that way when it was created.

--
Paul Russell
Senior System Administrator
University of Notre Dame