Our company recently switched it’s email server from Exchange Server. Not thinking, I deleted the Exchange item: Tools / Account Settings / Email / Remove. Not a good move!
Normal Outlook data files are PST files (e.g. outlook.pst). Exchange Server files are .OST files. Microsoft intentionally do not provide a way to convert an OST file to a PST file! Oh shit! There are commercial solutions and other solutions that may or may not work to convert the file.
After the panic subsided, I realised that I still had the company’s Exchange Server setup on my old laptop’s Outlook. So, I copied the OST file across to that laptop (so I had the emails that were present at the time I stopped using Exchange), fired up Outlook which told me the server was AWOL (which didnt matter), all my email and folders were there! Phew.
I then Archived ALL the folders (File / Archive, etc which copies the data to a PST file – e.g. archive.pst). I then copied the archive.pst file back to my new laptop, started Outlook and voila, all the old email was available.
So, the moral is, if you are switching from Exchange and not migrating your old email to a new mail system, ARCHIVE all your old email BEFORE you disconnect the Exchange data file from Outlook!