MY Outlook 2021 file has been changed to an .ost file from a .pst. How to I convert back to a .pst file

Edwin · Jul 20, 2025

antspants said:
if OneDrive was somehow a culprit

Guud Lurd!!!
Outlook glitches with OneDrive involved..., might as well stop the planet and get off!!!

Marcus Vinicus · Jul 20, 2025

This is from ChatGPT and I understand it to be correct.

I think its very unlikely that a) OneDrive is some sort of culprit or b) MS is monkeying around with this sort of stuff in a 2021 version of Outlook. Microsoft is much more focused on working on New Outlook currently. This is borne out by searching the Microsoft 365 Roadmap which is in my experience very up to date and reliable. There is no mention of changes to .pst files in anything other than New Outlook.

Changes to .ost files aren't listed at all.

Edwin · Jul 20, 2025

Seriously man, I thought this tech was obsolete!
If I need to save an email, I drag it to a folder..., the rest get deleted!

antspants · Jul 20, 2025

Marcus Vinicus said:
This is from ChatGPT and I understand it to be correct.

It is correct, great table. Nice find, thanks. Ima steelz eeet

antspants · Jul 20, 2025

Edwin said:
Seriously man, I thought this tech was obsolete!
If I need to save an email, I drag it to a folder..., the rest get deleted!

View attachment 139870

That’s a nice way to do things if you’re not holding 15 years of emails because you’re freaked out about being sued again due to not being able to prove what took place in a handshake business transaction. I know, my bad, but none the less.

PST files are a nice file system.

Edwin · Jul 20, 2025

antspants said:
PST files are a nice file system.

I'll take your word for it!

I've never used it..., I don't even think I know how!

antspants · Jul 20, 2025

Microsoft is aware that PST files are still very widely used, hence reincorporating them into the New Outlook interface/setup.

At present (I’ll happily stand corrected) the next phase is allowing the use of PST files but in a limited capacity.
You can add a PST file to the New Outlook interface
You can send (reply) from any folder in the PST file
You cannot currently add a POP3 account that is linked to a PST file.

Mass exodus if they kill PST files, but that’s just an opinion.

Edwin said:
I've never used it..., I don't even think I know how!

It’s simply a local filing cabinet for Outlook that lives on your PC, my man.

Marcus Vinicus · Jul 20, 2025

antspants said:
It is correct, great table. Nice find, thanks. Ima steelz eeet

Pony up some royalties first to compensate me for the time it took and all the stress involved!

antspants · Jul 20, 2025

Marcus Vinicus said:
Pony up some royalties first to compensate me for the time it took and all the stress involved!

lol You get 10 “Royalties”

Hornblower409 · Jul 20, 2025

Slowvince said:
the .pst file [disappeared] during an update

Any chance that the "update" was a change from the Windows Store version of Office to the Click-To-Run version?

The Windows Store Outlook App | Slipstick Systems

installing Click-to-run version will delete all settings, Outlook profiles - basically everything stored in the registry and AppData\Local and AppData\Roaming paths. If you use an IMAP account with 'This Computer only" folders, you need to export the contents of those folders before you switch to Click-to-run.

MY Outlook 2021 file has been changed to an .ost file from a .pst. How to I convert back to a .pst file

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