Recently I had a user whose PST files were in a default location, but that location was on a redirected folder network share. Apparently PSTs on network shares are a recipe for trouble, so I decided to move it to the local disk.

There's a registry key HKEY_CURRENT_USER\Software\Microsoft\Office\xx.0\Outlook\ForcePSTPath that can be used to force Outlook to search outside the default folder setup, for a given PST

I quit outlook, moved the PST, set the registry key and launched outlook again. It seems that Outlook found the existing file, created a new empty one alongside it with (1) after the name, reconfigured the settings in the Mail control panel to use the new empty one and proceeded to download all mail (IMAP server) again.

I quit outlook again, deleted the new one, duplicated the original large one to have the same name as the just-deleted one and launched outlook, to find that it moved the goalposts again, creating another new empty one, this time with a (2)

Try as I did, searching and modifying the registry (and finding something promising in a Catalogs subkey, that seemed to be a list of all the PST files ever known and used on the machine) I just couldn't get outlook to re-use the old PST in the new location

We've succeeded in doing this only once (moving the PST) using a different technique; don't use the ForcePSTPath key, just move the network folder locally, and then establish a symbolic link so the local PST folder becomes "mounted" at some part of the path that Outlook will try to use.

I was hoping to avoid this route, and instead use direct configuration. I've even found blogs that say it can be done this way (or blogs that recommend to just move the PST, and the next time Outlook is started it will prompt for its location) - neither of these worked out. I came to suspect that the PST had some internal signature that had somehow gone out of sync with the one the mail control panel/outlook was expecting.

If I see this SU answer: Outlook 2010 + Move IMAP PST file = Outlook data file cannot be accessed there's a specific caution in one of the answers not to restart the mail control panel otherwise it will recreate the files (new internal signature?)..

  • No; There is nothing internal to the .PST that indicates it's location – Ramhound Aug 31 '17 at 10:57
  • How do you explain Outlook's refusal to use an old PST copied over the top of a new PST? It's not about location, I think.. it's about something that identifies a particular PST as being paired with a particular email account. I did something to either damage the file internally, or cause outlook to generate a new file with a new signature that then meant it refused to accept the old PST even though it was named the same... When setting up a new mail account there's an option to "use an existing PST" but only for POP3. The option hides upon choosing IMAP, PST re-use seems not just "same name" – Caius Jard Aug 31 '17 at 12:13
  • I have never had a problem moving my .PST files around. I have carried the same .PST files with me for years. – Ramhound Aug 31 '17 at 12:55
  • POP3, or IMAP though? – Caius Jard Aug 31 '17 at 17:09
  • IMAP would be a .OST file anyways. .PST would be the files that were archived and/or POP3 – Ramhound Aug 31 '17 at 17:14

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