ipcop support

Dear Pro's,
I have recently installed IPCOP so that I can stop the abuse of the internet service in my company. I do not have an internal mail server, but instead users POP all my mails from external sources. I have enabled Ports 25 and 110 for external access on my IPCOP box.

I also downloaded and installed URL-Filter Add-on which can block users from browsing the internet during office hours 8am-5pm.

However, since i've blocked internet usage, I have some incoming mails that have "HTTP" e-mail signatures embedded in them. My users have a problem when sending mails / replying mails with these type of e-mails in outlook, outlook hangs endlessly.

I have an internal Mail server at my other office, and I don't have this problem, only with this office where i dont have an internal mail server, the users outlook hangs when IPCOP tires to deal with e-mails with "HTTP" e-mail signatures.

I am certain that this issue is being caused by IPCOP, because i disabled IPCOP for 1 week at this office (where clients dont have an internal mail server) and outlook didnt hang any more, once i retruned the IPCOP Box back into the picture, the problem started again.

Kindly revert with a suggestion as to how to deal with this situation with regards to IPCOP and "HTTP" e-mail signatures.

Really appreciate your help.
Regards,
Feroz