After OS reinstall, which Outlook file should I restore back into Outlook; the .pst, or the .ost?

The PST files are the ones to restore. OST is an offline cache file which is recreated when the client accesses Exchange server.

Ok.  And should I leave the pst there, or is it better/easier to switch mail delivery to the Mailbox on the server?

I meant should I leave the pst as the default mail delivery location.  Sorry.

Dear Mark88,

Off-line Storage Table (.ost) files are created automatically when you add New Email User Account and it's communicate with exchange server.

Personal Storage Table (.pst) are files which we create as a type of backup or additional copies in local system of email messages, calendar events, and other items.

Kindly keep us posted.


joyofsharing ( ^ _ ^ )

Hi there just to add also yes the PST is the file which you need. as mention above if you have space you can leave it on the server where the data is protected in RAID, but if you have a lot of people which have Outlook account and if all of these PST files are on the server so eveone use PST from the server this can decrease the performance on the server (of course it depens from the server type and the users requests), I will suggest you if the users are too many to instruct them to use web mail version, by this way you dont have to configure outlook on each separate PC, they can change the PCs, it willl be possible without swapping the pst file because its on the server. And because their mails (PST files) are on the server they are protected with RAID.

I was able to get with my friend who runs the Exchange Server at home.  I am going to call this upgrage from Outlook 2007 to 2010 "very complex".  Maybe it's because it's on a home network.  Just a couple notes: 1.) .pst’s from 03 or 07 are NOT compatible with 2010.  Must create an empty pst in 2010 first and then you’ll be able to import your old pst.  2.) Had to delete first entry in Data File Management which made my pst the delivery location.  (Outlook put a default entry in Data File Management)  3.)   Had to Change Folder button in Data File Management to force the server to deliver mail to the pst and not the Inbox in the the lower folder tree.

There are other things that the Server admin and I worked on last night for about an hour and a half.  

The overall configuration steps were complex in my opinion.  There's no way I would've been able to do this on my own.