I'm in the process of planning our migration from an internal hosted POP3-server (dovecot) to Exchange 2010. We're using Outlook 2003 for the moment, but will soon upgrade to Outlook 2010.

The big problem is that we have about 50 computers here in our HQ, plus ~30 clients in branch offices (wich will get their Exchange migration later sometime). I'm the only IT personel, and having to go around and manually set up Outlook and copy over their PST contents is not a option I'm looking for.

Some users have set outlook to keep messages for X number of days on the POP3 server, others have not. Using a POP3 connector to transfer over the mails is not a viable option.

Here is what I've done so far:

• Created a transform for the Office 2003 administrative installation point
• Created a .PRF file to modify any existing e-mail account to switch over to Exchange (including the RPC-encrypt hotfix described in MSKB 2006508)
• Tested both transform and PRF, both works
• Created a test-OU and GPO containing the Office 2003 installation with transform applied, also works

My big question is: How can I force Outlook to import any existing .PST into the new Exchange mailbox when the user starts up Outlook for the first time after the MST/PRF have been applied? Is this possible?