Migrating e-mail is very difficult, especially if you're like me and decide to setup your own e-mail server. The biggest problem I had was my e-mail getting falsely classified as spam:
I've also occasionally found really old services that use my old e-mail account. Even thought I have the password, they still require e-mail verification; which can't be done because the gmail account doesn't exist and it bounces.
Just use google apps, $5 a month gets you unlimited domains, an account with like 40+ aliases, email, and all the other applications. Setup SPF, and DKIM records, and away you go. There's no reason to deal with running your own email service at this point.
http://penguindreams.org/blog/how-google-and-microsoft-made-...
I've also occasionally found really old services that use my old e-mail account. Even thought I have the password, they still require e-mail verification; which can't be done because the gmail account doesn't exist and it bounces.