I recently got mail at my domain working properly, and as a result, I've changed my main email address. Of course, I'd like to get everything converted over. One thing that's tied to my email address is my MS passport, which of course runs everything from my MSDN subscription to MSN Messenger to my XBox live account (and very well I might add). Fortunately, you can change your email address from www.passport.com. I had 2 issues when doing so.
First, I had tried out the windows live custom domains beta, which hooked my domain up with hotmail addresses. It had some issues, so I had cancelled my service. But, when I tried changing my email address, it said marklio.com was reserved and I couldn't use it. Luckily, a few emails to passport and custom domains support cleared that up.
The second problem involves MSN Messenger. All passports have a unique ID underneath that is your actual "ID", even though you don't really see it anywhere. This allows you to change the email address without changing "identities". Most things migrated seamlessly (XBox360, etc). And signing into messenger gave me my contacts list. The problem was that none of my contacts were ever online. As it turns out, the entries in the contacts list ARE tied to email addresses instead of the unique IDs, so everyone on my list has my old address in their list.
Booo. So, if I'm on your MSN messenger contact list, please re-add me with my new email address. It's mark at this domain (marklio.com).