Trying to fix this issue for someone else, they've got a computer with Windows running on an SSD (C: ) that only has about 100GB of usable space, and a 2nd 1TB drive (D: ) for data. By default, their Outlook data file is on the C: drive, no surprise there, and naturally that's eating into that 100GBs pretty quickly. So just relocate the data file to the D: drive, right? Simple as that. Well...

I can't figure out how in the world to make this happen. I've googled it and found a couple of solutions, but none of them seem to work.

The first suggestion was to just manually move your data file, and when you restart Outlook a prompt will pop up that your data file cannot be found, and then you just point Outlook to the new path. That method no longer works. As soon as you start Outlook, a new data file is automatically generated in the old location.

Next, I found that you can manually move the data file, but instead of then opening Outlook, you have to go Control Panel > Mail > Data Files and point to the new path of your data file there. But again, as soon as the Data Files window is opened, a new data file is just generated in the old location..

Then I found that you need to manually move your data file to the new location, then you create a new profile in Outlook, select your existing data file in the new location, then set that profile as your new default in Outlook. When i try this method, the existing .pst is not recognized as a valid Outlook Data File and it cannot be selected.

Not sure if it's relevant, but this is the Office 365 version of Outlook and our email accounts are hosted through G Mail for Business/G Suite. I worked on this for 4 hours yesterday and got nowhere. Please help me before I pull all of my hair out.

Try installing Office on the alternate drive and running it from there. I actually work for Microsoft, so let me talk to a few people smarter than me and I'll come back.

Also, try this link for some tips. I'm waiting for my tech team to respond to my ping.

How to move Offline Outlook Data File (OST) Data (stellarinfo.com)

koadie said:

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Try installing Office on the alternate drive and running it from there.

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This crossed my mind, but it appears to not be so straight forward either. Looks like it requires some workarounds or registry edits.

I suspect you can stop outlook move to where you want and put a junction in its place pointed to its new location and outlook. Will be none the wiser. I know it works for directories, files are slightly different but typically they automatically dereference the symbolic link.
I also use this trick to include specific directories to be pushed to my onedrive by making a junction. To them in my onedrive folder

One thing to keep in mind. The outlook data file is the .ost, not the .pst. A pst is an archive file, that can easily be imported once you've got the ost sorted out

I haven't forgotten, my buddy has been out of office. I'm sorry.

OST files are what you have if your mailbox is hosted on Exchange. PST files are only "archives" if you are using Exchange but decide to open a secondary data file to back stuff up from Exchange mailbox.

So for anyone not on Exchange (POP3, IMAP etc.) you'll have a PST.

Now, Outlook has a quirk where if you move a data file, it thinks it is a new data file, so if you have your Outlook account set to "Leave a copy on the disk for XX days", it will try to redownload that number of days of email when you move the file. This is annoying because you end up with duplicates of your last two weeks of email. Most of us have this because it is now the default setting - reason being so you can get your email on your phone etc. If you don't have this setting, whichever device (phone or computer) checks your email server first downloads the message and deletes it, so you don't get it on the other device. So we have to be a little sneaky.

1) File -> Account Settings -> Account Settings -> Double-click your email account
2) Uncheck "Leave a copy on the server" -> Next -> Done
3) Click Send/Receive in the toolbar, then Send/Receive all Folders. This will take a few minutes because it is deleting the email from the server.
4) Quit Outlook
5) Move PST file to D: drive
6) Launch Outlook. It will create the new file.
7) File -> Account Settings -> Account Settings -> Data Files tab
8) Add -> Browse to PST file on D: drive and open
9) Click "Set as Default" to make the newly opened PST file the default
10) Close the accounts window -> Quit Outlook
11) Count to 5 to give Outlook time to do some crap in the background
12) Launch Outlook
13) File -> Account Settings -> Account Settings
14) Make sure "Deliver to" is pointed to the Inbox on the old PST file, not the newly opened file.
15) Data files tab -> Click the non-default PST file (the one it created temporarily) and remove it
16) Double-click your email account -> Check the "Leave a copy on the server box" -> Next -> Close

Disclaimer: OCCASIONALLY you will not be able to complete step 14. Step 11 seems to help prevent that. But if you can't, you have no choice but to go into the Mail control panel, delete your profile, and set your profile up from scratch. But then you can follow the steps above to select file correct PST file again.

I heard back from my friend this morning. He sent me quite a bit of info, but he's super busy so this is the best I can do.

If you can't change your .ost file location click here

for the .pst he said the following:

Once the ost fix is done the archive can be manually moved to the new location in one of two ways

A. (exit out look>nav to file location in file explorer> copy file > paste to new save location)

Or

B. From the outlook interface simply create a new archive once the ost has been moved (recommended)

Let me know if this helps if not he said he'll run it up the chain.

Thanks for the input guys. Unfortunately i'm not going to be able to take a look at that computer again for another week or so. I'll update when i can try some of this stuff out and let you know what works.

UmustBKidding said:

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I suspect you can stop outlook move to where you want and put a junction in its place pointed to its new location and outlook. Will be none the wiser. I know it works for directories, files are slightly different but typically they automatically dereference the symbolic link.
I also use this trick to include specific directories to be pushed to my onedrive by making a junction. To them in my onedrive folder

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For those of you wondering, this was the winner. Thanks for the help everybody.