Pete Turnbull <pete(a)dunnington.u-net.com> writes:
Options I can think of:
a) silently discard any such postings (probably not a good idea)
b) bounce them back to the author, with an explanation of why bounced
c) remove the non-text part
d) combination of (b) and (c)
e) accept, but warn the author (who may not realise (s)he's sent HTML)
All of these would involve scanning the content to a greater or lesser
extent.
For options a and b, only the header needs to be examined. If there is
a Content-Type header that specifies anything other than text/plain,
or if there is a Content-Transfer-Encoding other than 7bit (or perhaps
quoted-printable, although that generally sucks also), the message should
be discarded or bounced.
In particular, this would discard or bounce any messages whose Content-Type
is multipart/mixed. If people want to supply files to the list, it should
be done by providing a URL, or by private email. No attachments should be
sent to the list.
IMNSHO. :-)