gmail account in outlook Classic

Hello,

This happens because the Gmail account needs to be reauthorized.

Please follow these steps:

Open Outlook.

Go to File → Account Settings.

Delete the existing Gmail account.

Click Add Account to add the account again.

Enter your Gmail address.

A Google sign-in page will appear for authorization.

Once the Google login window appears and you complete the authorization, the synchronization should normally be restored.

Have you run into this known bug?

https://support.microsoft.com/en-us/office/unable-to-add-a-gmail-account-to-classic-outlook-4d9530c5-3f40-4e6d-9b45-4477f160828f

The article title is "Unable to add a Gmail account ..." but I have seen reports that this bug can also cause working GMail accounts to fail. The fix is the same - Clear the Windows Credentials.

The Gmail/Outlook Classic sync issue is a known problem related to how Gmail accounts authenticate in classic Outlook. Use the following steps to restore syncing.

1. Confirm IMAP is enabled in Gmail
   • In a browser, sign in to Gmail.
   • Go to Settings (gear icon) > See all settings > Forwarding and POP/IMAP.
   • Under IMAP access, make sure Enable IMAP is selected.
   • Select Save Changes.
2. If Outlook shows an IMAP setup error or stopped syncing suddenly
   • This can happen if the Gmail permissions for Microsoft apps & services are not correctly granted.
   • First, remove the old access and cached credentials:
   Step 1: Remove Microsoft apps & services access in Google
   • Close Outlook.
   • Sign in to your Google account at Google.com.
   • Select your profile picture > Manage your Google Account.
   • Go to Security.
   • Under Your connections to third-party apps & services, select Microsoft apps & services.
   • Under Access you've given to Microsoft apps & services, choose Remove all access, then Confirm.
   Step 2: Remove cached Google IMAP credentials in Windows
   • Open Credential Manager (from Start, search for Credential Manager; on some systems open Control Panel first).
   • Select Windows Credentials.
   • Under Generic Credentials, find entries starting with MicrosoftOffice16_Data:OAUTH2.
   • Expand each and hover over the name until the full value shows tp_google_imap_oauth2.
   • Remove each credential that matches MicrosoftOffice16_Data:OAUTH2 (there are typically two per Gmail account).
3. Reconnect Gmail in classic Outlook
   • Open Outlook.
   • If the Gmail account is still in the profile but not syncing, use the Sign in via browser or Retry link when prompted and complete sign-in.
   • During the Google sign-in, on the permissions page, ensure the checkbox is selected for:
     • Microsoft apps & services can access: “Read, compose, send, and permanently delete all your email from Gmail.”
   • If the account was removed from Outlook:
     • Go to File > Add Account.
     • Enter the Gmail address and select Connect.
     • Sign in with the Gmail password in the browser window and select Allow on the permissions page, making sure the above permission is checked.
4. If Outlook won’t accept the Gmail password
   • For older classic Outlook builds that do not support the newer Gmail sign-in flow, an app password may be required instead of the normal Gmail password.
   • In that case, configure two-factor authentication in Google and generate a Google app password, then use that app password in Outlook.
5. If automatic setup still fails
   • Use the advanced/manual setup in classic Outlook and configure the account as IMAP using Gmail’s IMAP/SMTP settings:
     • Incoming (IMAP): imap.gmail.com, SSL, port 993
     • Outgoing (SMTP): smtp.gmail.com, SSL/TLS, port 465 or 587, authentication required

After completing these steps, Outlook Classic should resume syncing the Gmail account.

References:

• Unable to add a Gmail account to classic Outlook
• Unable to sign in or add a Gmail account to classic Outlook
• Add a Gmail account to Outlook for Windows
• Troubleshoot Outlook email setup
• Fix problems connecting your Google account to the Microsoft Cloud
• gmail accounts no longer working in outlook classic - Microsoft Q&A
• search for solutions another user has found - Microsoft Q&A