I'm confused by Sea Urchin's last 3 sentences. I use imap and Outlook 2007 (before that Outlook 2003). I find that the imap email account creates its own inbox separate from the main Outlook in box. Within the imap inbox I have 2 subfolders with appropriate message rules. These automatically sync with all of my devices.

Have re-read the previous postsI want to clarify a point. If the emails he already has have been downloaded onto Outlook and not left on server then they will not be lost. They should be regularly backed-up and archived. I keep a back up pst file for each account. If they have been left on server they could be available for download again. Personally I would back them up before the change.

A thing to watch is the limit of emails on the server. I regularly move old emails to archive folders and off the server, then back up the archive folder. Then I purge the imap folder of these old emails.

I could have phrased that better! If he has already downloaded the emails to Outlook and has them backed up then they should not be lost when using pop3.

lotvic & Sea Urchin - I'm sorry but what is the problem with subfolders in the inbox? I'm not aware of any problem with that. If it is do with size then you should regularly archive old e-mails and this can be set up automatically.

Mustn't hijack thread but there's usually a single pst file in Outlook (more for imap) so if that gets corrupted then not just the inbox gets corrupted. Outlook 2010 has conversation mode. I was wondering what the problem is with subfolders.