Outlook Change File for All Contacts
Yes, you can change the Outlook data file (.pst or .ost) that stores your contacts, and you can apply that change to all contacts in that file at once. The key is to understand that Outlook does not let you move individual contacts between data files with a simple drag-and-drop that preserves all fields; instead, you export the entire contacts folder (or all contacts) to a new or existing data file, then set that file as the default delivery location for new items. This article explains the exact steps, the differences between .pst and .ost files, and common pitfalls.
What Are Outlook Data Files and Why Change Them?
Outlook stores your mail, calendar, tasks, and contacts in a data file. There are two types:
- .pst (Personal Storage Table) – used by POP3 and IMAP accounts, and for archiving. You can create multiple .pst files and move folders between them.
- .ost (Offline Storage Table) – used by Exchange, Microsoft 365, and Outlook.com accounts. It is a cached copy of the server mailbox. You cannot directly move items between .ost files; you must export to a .pst first.
Changing the data file for contacts is often needed when you run out of space, want to keep personal contacts separate from work, or need to transfer contacts to a new computer.
How to Change the Data File for All Contacts
The process differs slightly depending on your account type, but the principle is the same: export the contacts folder to a .pst file, then (if needed) set that file as the default. Here are the steps for Outlook 2016, 2019, 2021, and Microsoft 365.
- Open Outlook and go to File > Open & Export > Import/Export.
- Choose Export to a file > Outlook Data File (.pst).
- Select the Contacts folder (or the folder that contains all contacts you want). Check the box Include subfolders if needed.
- Choose where to save the .pst file and give it a name. Click Finish.
- Now, to make Outlook use this new file for all future contacts, go to File > Account Settings > Account Settings.
- In the Data Files tab, click Add and select the .pst you just created.
- Select that new file and click Set as Default. This makes Outlook deliver new items (including contacts) to that file.
If you are using an Exchange or Microsoft 365 account, you cannot set a .pst as the default delivery location for new mail – the server mailbox remains the default. In that case, you can still create a .pst and move contacts into it manually, but new contacts will go to the server mailbox unless you change the account’s delivery location (which is not recommended for Exchange).
Moving Contacts Without Losing Fields
Many users try to drag contacts from one folder to another and find that some fields (like custom phone numbers or categories) are lost. This happens because dragging creates a new item with only the default fields. To preserve all data, use the export/import method described above. Alternatively, you can use the Move to Folder command (right-click contact > Move > Other Folder), which preserves all fields because it moves the actual item.
If you want to copy contacts (not move) while keeping all fields, export to a .pst and then import that .pst into the destination folder. The import will create exact copies.
How to Choose the Right Data File for Your Contacts
Consider these factors:
- Account type: For POP3/IMAP, you can use any .pst. For Exchange/M365, the default is the server mailbox (.ost).
- Size: .pst files have a default size limit of 50 GB (older versions had 20 GB). If you have many contacts with attachments, keep an eye on size.
- Portability: A .pst file is a single file you can copy to a USB drive or cloud storage. An .ost is tied to the server and cannot be moved.
- Backup: If you want to back up contacts, export to a .pst regularly.
Common Problems and Fixes
Problem: “The file is in use� or “Access denied� when opening a .pst. Close Outlook, make sure no other program (like a sync tool) is using the file, and try again. If it persists, restart Windows.
Problem: Contacts disappear after changing default file. This happens if you set a new default but didn’t move the existing contacts. The old contacts remain in the old file – they are not deleted. You can still see them by expanding the old data file in the navigation pane. To make them appear in the new default, move or copy them using the export/import method.
Problem: New contacts go to the wrong folder. Check the default delivery location: File > Account Settings > Account Settings > Data Files tab. The default file is marked with a checkmark.
Problem: Cannot set .pst as default for Exchange account. This is by design. Exchange accounts must use the server mailbox. You can still create a .pst and manually move contacts there, but new items will go to the server.
Comparison: .pst vs .ost for Contacts
| Feature | .pst | .ost |
|---|---|---|
| Used by | POP3, IMAP, archive | Exchange, M365, Outlook.com |
| Can change location | Yes, freely | No, it’s a cache of the server |
| Can move contacts between files | Yes | Only via export to .pst |
| Backup | Copy the file | Not recommended – sync with server |
Safety and Data Integrity
Before making any changes, back up your contacts. In Outlook, go to File > Open & Export > Import/Export > Export to a file > Outlook Data File (.pst) and save a copy. Also, do not delete the original data file until you have verified that the new file contains all contacts. If you are using an Exchange account, remember that the server is the authoritative source – changing your local .ost does not affect the server data.
Frequently Asked Questions
Q: Can I change the data file for only some contacts? Yes, you can move individual contacts or a subset by selecting them and using Move > Other Folder. But to preserve all fields, use the export/import method for the entire folder.
Q: Will changing the default data file delete my old contacts? No, the old file remains intact. You just change where new items are saved. Your old contacts are still accessible in the old data file.
Q: How do I know which data file my contacts are in? In the navigation pane, right-click the Contacts folder and choose Properties. Look for the location path at the bottom of the General tab – it shows the file name and path.
Q: Can I use a network drive for a .pst file? It is possible, but not recommended because it can cause corruption and performance issues. Microsoft does not support .pst files on network shares.
Q: What is the maximum size for a .pst file? For Outlook 2016 and later, the default limit is 50 GB. For older versions, it was 20 GB. If you exceed the limit, you may see errors or be unable to add items.
Related
Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.