I switched the Evo setup to use IPs, and starting moving mail. Everything looks good. Then I updated the DNS and sent a test, and it went to the new inbox. Still good.
Then I went to move the last couple of folders, and it started getting flaky. Not always pulling up the message bodies, but not always failing either. I saw a message flash past in the status bar about problems reading 'imap.cooklikeyourgrandmother.com', but the Evo setup isn't using the subdomain any more.
Is it possible I'm hitting it via IP, but the server is redirecting based on DNS?