gnus posts fail with 441 error (rejected by POST filter)

[Deon Garrett]

Whenever I try to post a followup from Gnus, the server rejects the post
with a 441 error "post failed (rejected by POST filter)" or some such.  I
can post the exact same followup within slrn without problems.  Gnus
generally manages to coax the server into accepting a post; it's just
followups that exhibit the problem.  I'm sure it's a server problem, but
I'd like to figure out what Gnus does to piss it off that slrn does not
do.

Any ideas where to look?

P.S.: I'm using BellSouth DSL, and there seem to be people with the same
problem using Outlook Express.  The only suggestion that I've seen that
seemed to work for some people was to delete their OE profile and start
again.  I tried OE and it worked fine for me.

-- 
Deon