1. I can't believe that someone would have ALL attachments blocked, that's bad admin. I'd strongly suggest double-checking that mate.
2. Zip files may only work NOT ALL attachments are blocked.
3. Be careful with file sharing apps. If you're not sure what you are doing, don't use them as they can be rife with viruses.
4. Try 'You Send It' from
www.yousendit.com. It atatches into OE and you can configure it to send all attachments via their web servers. The recipient (who has attachments blocked) will receive your email with a link on it to download the file from. The recipient does NOT need to install anything.
5. Messenger app? MSN Messenger, Yahoo Messenger. Surely you've heard of these?
Your best would probably be the YouSendIt plugin for OE, its free and works really well.
There is also a prog called PANDO, but that involves an install on the recipient pc also, which is not always practical.