Yesterday here at Yahoo my mail server was migrated to new Microsoft Exchange server 2003 from the earlier IMAP server. As usual all my mail clients (Linux Fetchmail/Procmail and Windows Outlook and Thunderbird) failed to connect. It was a big pain to setup the whole thing back and re-creating the old IMAP rules to new Exchange server as there was not any auto migration.
Anyway, after configuring the Outlook with the new Exchange 2003; I re-wrote all my existing IMAP rules to server side and re-created all the folders. Once that is done, I can even access the new mail using Outlook Web Access (OWA). Once this step is done, I re-configured my Thunderbird client by subscribing to all folders in the exchange and things are back to normal. I prefer Thunderbird over outlook because of one of the internal Thunderbird plugin that allows to complete details of the sender if the sender is a yahoo employee.
By default the Fetchmail did not work on my Linux box where I fetch and forward a copy to another IMAP account which is accessible via my iPhone. And noticed that the old IMAP sub-folders which were like “INBOX.BLABLA” is not working with Exchange and instead needed to change it to “INBOX/BLABLA” in order to get rest of the sub-folders. I also needed to get rid of SSL support in order to get fetchmail to work.