Here is a problem discovered by a fellow technician. He was in the process of rebuilding a laptop after a BSOD. So he performed an offline backup of everything on the hard drive, before rebuilding the operating system. He had a list of all the necessary passwords, keys, etc., so he thought that he was safe…
However, when he got to reinstalling and setting up Outlook he encountered a problem. The OST file is not portable. When Outlook is setup to use an Exchange server, there is an option to cache the data on the local computer, and thus creates an OST file. Typically, in a standard environment, there is no problem – just delete the OST file and reconnect to the Exchange server – the OST will automatically recreate and you’re all set. However here was the unique situation of this setup:
The laptop was part of a different domain as he was an outside consultant for the company. He did have a corporate Exchange account on his laptop, but since he was assigned to this client, he was no longer using his laptop to connect to the Exchange server for whatever reason, instead he simply used Outlook Web Access. However, at the client site, he did have a POP3 e-mail account, which was setup to put it’s mail inside his Exchange Personal Folder within outlook. No problem here, pretty standard to use Exchange and then POP an alternate account and have it all dump into the same inbox. Even though he was no longer connected to the Exchange server, everything was dumping the OST file. When the POP would occur it would delete the files off the mail server (again, nothing new)…
However, if you haven’t already figured it out, the only place the e-mail lived was in the OST. (Compare that to a straight POP profile in Outlook without Exchange, which places mail in a PST file.) Yet, the OST is not portable. So it isn’t something you can simply mount in a new profile/build/rebuild/reprofile/whatever of Outlook. The results was an orphaned OST file which couldn’t be connected, and about two years of lost POP mail. Had he periodically connected to the Exchange server via his laptop (VPN or RPC-HTTPS), it would have synced the POP mail to the Exchange server so the OST could be rebuilt. But in this case, if you connected to the Exchange server, the OST would have rebuilt from the last point it was synced – plus any new Exchange only e-mail. Thus all POP mail was lost.
Now there are tools available on the internet to recover an OST file which pretty much work as promised. However the only one which actually work are around $300, or you can pay someone online about $100 and they basically run that tool on your file for you. From experience, the tools which are less than $300 only do a partial job, not sure why, but I guess you get what you pay for.
Of course, the best thing is to know what you’re getting into. One good way to get around this would have been (before you rebuilt the computer) to create a new PST file and then manually move all the contents of the OST file to the PST file within the Outlook profile the OST is associated with.