Two possibilities. First, Outlook Express/Mail outbound queue might be
stuck. Microsoft and ISPs have some bugs in their crap. ISPs are often
now rate limiting and exaserbates some Microsoft bugs. If you have this
issue, look in the Outbox. If you see the stuck messages, this is your
issue. The best way to recover is reboot your PC, open mail, send then
when it fouls up shut the PC off for 4 hours and repeat until the messages
are clear.
Next one is Microsoft does filter on their end. If you post to a MS
server, try using the ISP. ISPs don't censor posts to a specific group.