Change outlook data file default

Question

Hi,

I use IMAP settings on Outlook 365, Windows 11 and have an *.ost data file but my default Data file is a *.pst, I'm not sure why it is there but when I try to remove it I get the message:

Can I change it to the *.ost datafile and delete the *.pst one? I think it must have been left over from when I first set up Outlook but I use IMAP not POP.

Thank you,

BeebleOz

Answer 1

Hi BeebleOZ Thank you for posting in Microsoft Community. I am happy to help. I am a user just like you and only trying to advice/ assist in a best possible way I could resolve your issue.

You're right to be cautious about changing the default data file in Outlook 365. While it's generally safe to switch from a PST file to an OST file when using IMAP, there are a few things to consider:

1. Calendar and To-Do Bar: As the message warns, the default PST file stores your calendar and settings for the To-Do Bar, Favorites, shared folders, and RSS feeds. Switching to the OST file will not move these items, and you'll need to manually migrate them or recreate them in the new data file.
2. Multilingual Unicode data: The message also mentions that the PST file may not provide full support for multilingual Unicode data. This shouldn't be a major concern unless you frequently work with languages outside the basic Latin alphabet. However, if you do, switching to the OST file could improve compatibility.
3. Backup your PST file: Before making any changes, it's crucial to back up your existing PST file. This ensures you have a copy of your calendar, settings, and other data in case anything goes wrong.

Here's how you can safely switch to the OST file:

Close Outlook. Open File Explorer. Navigate to the location of your PST file. The default location is usually C:\Users<username>\AppData\Local\Microsoft\Outlook. Copy the PST file to a safe location, such as an external drive. Launch Outlook. Go to File > Account Settings > Account Settings. Select the IMAP account you want to use with the OST file. Click Data Files... Click Set as Default next to the OST file.** Click OK twice. Restart Outlook. Your Outlook data will now be stored in the OST file. You can then delete the old PST file if you're confident you won't need it anymore.

Tips: If you're unsure about any of the steps, consult the official Microsoft documentation: https://support.microsoft.com/en-us/office/open-and-close-outlook-data-files-pst-381b776d-7511-45a0-953a-0935c79d24f2 Consider using the Import/Export feature in Outlook to manually migrate your calendar and other data from the PST file to the OST file if needed. If you encounter any issues after switching to the OST file, you can always revert back to the PST file by following the same steps and setting it as the default data file. I hope this information helps! Let me know if you have any other questions.

Kind regards -Adedayo</username>

Answer 2

Hi Adedayo,

Sorry for the delay in answering you.

Your information helped a lot. I should have mentioned though that only the *.ost files are in C:\Users&lt;username>\AppData\Local\Microsoft\Outlook. The *.pst files are in C:\Users&lt;username>\OneDrive\Documents\Outlook Files which I want to remove because of sync problems every time I open Outlook.

I think I can safely remove the pst Outlook data file and then remove the Outlook folder from OneDrive.

I just thought I would edit my message. Everything worked out well.

Thank you,

BeebleOz