How to merge email from old outlook with outlook 365

Question

My Outlook 2016 stopped operating and provided a message store issue error. I wasn't even able to delete anything. It simply stopped and won't even allow me to see some emails in some cases. After a month of try to delete, I purchased Microsoft 365 today. I would like to have my emails back from the original version and either have them in the new 365 or have the upgrade I made recognized by my old format (which I prefer). Can anyone tell me how to do this? My 365 account shows not one single email.

thanks.

Pam

Answer 1

Hi @Pam R

Thank you for reaching out. 

As far as I know, the “message store issue” in Outlook 2016 is most commonly caused by the local PST data file either reaching its size limit or becoming corrupted. This can prevent you from deleting emails or accessing certain messages. 

Since you have already upgraded to Microsoft 365, the recommended approach is to repair your existing PST file and then move your emails into your Microsoft 365 mailbox for better reliability and cloud-based access. 

To troubleshoot the issue, you could follow these steps: 

First, try to locate your .pst file, which is typically stored in the Documents\Outlook Files folder or in C:\Users\YourUsername\AppData\Local\Microsoft\Outlook. You can also use Windows search and look for “Outlook” or “*.pst” to find it. Once you locate the file, it is recommended to make a backup copy before proceeding. 

Next, run the Inbox Repair Tool by navigating to C:\Program Files (x86)\Microsoft Office\root\Office16, then double-click SCANPST.EXE. Select your PST file and start the scan, then proceed to repair any errors that are found. 

You can refer via: Repair Outlook Data Files (.pst and .ost) - Microsoft Support 

After the repair is completed, open Classic Outlook from your Microsoft 365 subscription. Go to File > Open & Export > Open Outlook Data File, and select the repaired PST file. Your old emails should now be visible. 

To transfer your emails, you could drag and drop folders or individual messages from the old PST file into your Microsoft 365 mailbox. Since you have a large amount of data, try to move the emails in smaller batches to avoid performance issues. 

Once the transfer is complete, you can close the old PST file, and all your emails will then be stored safely in Microsoft 365. 

I hope this helps.  

Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution.  

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Answer 2

To get the old Outlook 2016 mail into Microsoft 365 Outlook (and keep using the classic Outlook interface), use a .pst export/import with classic Outlook for Windows.

1. Confirm classic Outlook is installed and used
   Importing from a .pst file is not supported in the new Outlook for Windows. If using new Outlook, turn off the New Outlook toggle to return to classic Outlook. If classic Outlook is not installed, install it as described in the export article’s note section.
2. Export the old Outlook 2016 data to a .pst file
   On the machine/profile where Outlook 2016 still has the data (even if it is unstable), export everything to a .pst file:
   • Open classic Outlook.
   • Follow the steps in Export emails, contacts, and calendar items to Outlook using a .pst file to create a backup .pst of the mailbox.
   • Save the .pst somewhere safe (e.g., Documents or an external drive).
3. Set up the Microsoft 365 mailbox in classic Outlook
   On the same or a new PC:
   • Open Control Panel → Mail → Show Profiles….
   • Add a new profile if needed and configure it with the Microsoft 365 email address and password so that Outlook opens and shows the empty Microsoft 365 mailbox.
4. Import the .pst into the Microsoft 365 mailbox (classic Outlook)
   With classic Outlook open on the Microsoft 365 profile:
   • Select File on the ribbon.
   • Select Open & Export > Import/Export to start the wizard.
   • Choose Import from another program or file > Next.
   • Choose Outlook Data File (.pst) > Next.
   • Browse to the .pst exported from Outlook 2016 and choose how to handle duplicates.
   • If prompted, enter the .pst password.
   • When asked where to import:
     • To merge everything into the Microsoft 365 mailbox, select that mailbox.
     • Or choose Import items into the current folder if importing into a specific folder.
   • Select Finish and wait for the import to complete.
   After this, the Microsoft 365 mailbox in classic Outlook will contain the old mail, contacts, and calendar items. If the account is an Exchange/Microsoft 365 account, the imported items will sync to the cloud and appear on other devices using the same account.
5. If only some items are needed
   Instead of a full import, the .pst can be opened and items dragged into the Microsoft 365 mailbox:
   • Use File → Open & Export → Open Outlook Data File to open the .pst.
   • In the folder list, drag messages/contacts/calendar items from the .pst folders into the Microsoft 365 folders.

This approach lets the Microsoft 365 subscription work with the preferred classic Outlook interface and restores the old Outlook 2016 data into the new account.

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References:

• Import email, contacts, and calendar from an Outlook .pst file
• Export emails, contacts, and calendar items to Outlook using a .pst file
• Migrate from Microsoft 365 Apps for enterprise to Microsoft 365 Personal for Windows 10
• Migrate from Microsoft 365 Apps for enterprise to Microsoft 365 Personal for Windows 7
• Migrate from Microsoft 365 Apps for enterprise to Microsoft 365 Personal for Windows 8.1