The exact symptom is that the message, as received by LISTSERV, ends
abruptly in the middle of an HTML sequence, before the actual message text.
Since the only thing in the truncated message is HTML style data, the
message looks blank.

This was originally reported as a bug in SMTPL (Windows only) because the
exact same message could be successfully delivered to a vanilla unix mailbox
with I think sendmail. But when we pasted the non-truncated message from the
unix mailbox into a session with SMTPL, it was delivered successfully. I
will also guarantee that SMTPL is not going to be confused by HTML
sequences. Anything it reads on the wire is random fodder to be written to
the output file, except of course for the ./.. escape sequences. SMTPL has
no concept of HTML tags, they are just yet more random bytes of data to be
saved to the output file. HTML does tend to have a lot of periods, but there
are no leading periods anywhere in the message and there should be no
double-period issue. Without a wire trace, it is not possible to know for
sure what has happened.

The problem could also be in the sending MTA, which I would assume to be
Exchange in most cases. It would be interesting to try the failing message
when sent with another MTA, for instance sendmail.

  Eric