Hotmail Not Passing Emails From Mail.app

An interesting trend has been observed by quite a few people on Apple's message boards. Seems Microsoft's Hotmail servers are not properly passing emails sent from people using Mail.app. It is not an isolated case and has been ongoing for quite some time. A user will send an email via one email client (Thunderbird, for instance) and it will go through fine, but an identical email sent via Mail.app just disappears into the ether.

The only good news here is that Microsoft appears to be aware of the problem (according to some ISP's) and is working on a fix.

Update: One work-around (as posted in the link provided above, and by Tim below) is this. If you're having this problem, send an email to yourself with the recipient's email address in the CC field. The email to you won't come through but the copy sent via the CC field will. No idea why, but it seems to work.