Watchguard firewall problem with Outlook Express 6/Hotmail interfacing

From:
Date: 10/29/02 

Date: 28 Oct 2002 23:29:54 -0800

Recently, the administrators of our partner organisations network, which our
organisation uses, have installed a Watchguard firewall. Since they have
done so, we have had numerous problems due to the initial configuration of
the firewall. One of the more subtle problems we have encountered is in
Outlook Express 6 and it's interfacing with Hotmail via HTTP.

It seems now that any email sent via Express/Hotmail, is not saved in Sent
Items, regardless of the Options setting. The emails are delivered, but not
saved, and no feedback given to warn of this. If I use an alternative
Internet capable network, this works fine on the same PC. It was also
working pre-Watchguard firewall. The symptoms are exactly the same as those
described by Keith Hayward in his post
http://groups.google.com/groups?q=outlook+express+not+save+sent+hayward&hl=e
n&lr=&ie=UTF-8&oe=UTF-8&selm=755401c1bbd1%2451262d60%243bef2ecf%40TKMSFTNGXA
10&rnum=1.

Can anyone help? The technicals of this would also be interesting to me.
Thanks in advance,
Shaddy