After installing 10.3 Mail.app is no longer able to fetch my mail. I am trying to use IMAP over SSL to a dovecot IMAP server. Initially Mail.app complained about the servers SSL certificate as it didn't know the root signing certificate. This was Ok as the certificate was self signed. I tried to view more details about the error message but Mail.app locked up and I had to force quit it. Next time I tried to tell Mail.app to ignore the error which it seemed to do however no mail now shows up. Mail.app does actually log in to the server...just doesn't fetch any mail. I have tried disabling SSL but it hasn't helped.
I haven't done too much investigation yet but wondered if anyone else has experienced something similar.