Approving posts with outlook

I am the administrator of a majordomo list on a server that I don't have
access to.  I had been using outlook 200 for bout 3 years to approve and
post messages with very few problems.  About a month ago, I upgraded to
Outlook 2003 and now realize that I can no longer post in html without
issues with encoding (since, as I understand it, majordomo likes plain
text).  

So, I have turned automatic encoding off, I have turned off removal of extra
breaks in plain text and I am using only plain text but I am still having
problems with invalid approval headers and with the messages being posted
containing the following information from the list server:

silver.ci.lexington.ma.us id RAA12664
Sender: [email protected]
Precedence: bulk

I never got these before and aside from my messages now looking crappy, they
also have this at the beginning.
Can anyone with some experience with outlook 2003 tell me what header
information I can safely remove when a message comes to me for approval
and/or any other helpful tips for formatting.  I can't seem to find this
sort of information on the internet in spite of having searched around for
the last two days.

Any help would be very much appreciated!

Ellen