How can I show older mails of my gmail account in new Outlook365?

Older Gmail messages are not automatically downloaded into the new Outlook for Windows; they must first be exported from Gmail into a .pst file using classic Outlook and then imported into the Microsoft 365 mailbox that is shown in the new Outlook.

To make older Gmail mail visible in new Outlook 365, use this process with classic Outlook for Windows:

1. Switch to classic Outlook (temporarily)
   If currently using the new Outlook desktop client, use the toggle in the upper-right corner to switch back to classic Outlook.
2. Add the Gmail account to classic Outlook and export to .pst
   In classic Outlook:
   1. Go to File > Add account.
   2. Enter the gmail.com address, select Connect, then Done after sign-in.
   3. Select the Gmail account, then go to File > Open & Export > Import/Export.
   4. Choose Export to a file > Outlook Data File (.pst) > Next.
   5. Select the Gmail mailbox, check Include subfolders, then Next.
   6. Choose Replace duplicates with items exported, browse to choose a save location, select OK, then Finish.
3. Import the .pst into the Microsoft 365 mailbox (classic Outlook)
   Still in classic Outlook, with the Microsoft 365 account configured:
   1. Go to File > Open & Export > Import/Export.
   2. Select Import from another program or file > Outlook Data File (.pst) > Next.
   3. Browse to the .pst exported from Gmail.
   4. Choose how to handle duplicates.
   5. In Select a destination folder, choose the Inbox (or another folder) under the Microsoft 365 account, then Next > Finish.
   This copies the older Gmail messages into the Microsoft 365 mailbox that the new Outlook will display.
4. Return to the new Outlook
   After import completes and mail is visible in classic Outlook under the Microsoft 365 account, switch back to the new Outlook for Windows. The imported mail will appear there because it is now part of the Microsoft 365 mailbox.

If the Gmail account itself should remain visible as a separate account in new Outlook, add it directly in new Outlook (View > View settings > Accounts > Email accounts > + Add Account) and Gmail will sync from the server; however, only server-retained mail will appear. Anything only present in local Outlook data must be moved via the .pst method above.

References:

• Move your old email, calendars, and contacts to Microsoft 365
• Set up Office 365 email in Outlook and Import Gmail