Classic Outlook not working

Question

Hi, I have been unable to send or receive Gmails in Classic Outlook, I have tried all the tips online but nothing works. I have attached a screenshot, any helps or tips please?

Regards from Lucas

Screenshot 2026-03-10 161334.png

Answer 1

Hi Lucas,

There is an ongoing issue related to yours:

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

https://www.yourwindowsguide.com/2026/03/gmail-not-working-in-outlook.html

• Press Windows + S, type Credential Manager, and open it.
• Click Windows Credentials.
• Scroll to Generic Credentials.
• Find entries starting with MicrosoftOffice16_Data:OAUTH2.
• Expand each entry.
• Hover over MicrosoftOffice16_Data:OAUTH2 to see the full name containing tp_google_imap_Oauth2 (these are Gmail credentials).
• Click Remove for each MicrosoftOffice16_Data:OAUTH2 entry.
• Remove both credentials for the affected Gmail account.
• Optional: To identify the correct Gmail account before deleting:
  • Open Registry Editor.
  • Paste this path in the address bar: Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities
  • Check the Identity subkeys.
  • The number at the beginning of the identity key matches the number in the MicrosoftOffice16_Data credential.
• After removing the credentials:
  • Open Outlook.
  • Go to the affected profile.
  • Click Sign in via browser in the Outlook notification bar.
  • Sign in to your Gmail account again.

Remove access for Microsoft Apps & Services in Gmail (Fix Gmail in Outlook Sync)

• Close Outlook.
• Go to google.com and sign in to your Google account.
• Click your profile picture in the top-right corner.
• Select Manage your Google Account.
• From the left menu, click Security.
• Scroll to Your connections to third-party apps & services.
• Select Microsoft apps & services.
• Find Microsoft apps & services has some access to your Google Account.
• Click See details.
• Under Access you’ve given to Microsoft apps & services, click Remove all access. This should reset the Gmail in Outlook sync, and you can try again.
• Select Confirm.

I hope this information helps. If you have any more questions, don't hesitate to reach out.

Otherwise, please take a moment to rate the answer. Wishing you good luck!

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Answer 2

For Gmail accounts in classic Outlook that suddenly stop sending/receiving, the issues in the provided material point to three main areas: connection state, Gmail/IMAP permissions, and app password/authorization.

Work through these in order:

1. Confirm Outlook is actually online

• Look at the bottom status bar in classic Outlook.
• If it shows Disconnected, Working Offline, or Trying to connect…, Outlook is not talking to the mail server.
• On the ribbon, go to Send/Receive tab → in Preferences group select Work Offline once to toggle it back online.
• Then click Send/Receive again and see if messages flow.
• If still not working, open a browser and verify internet access by going to http://www.microsoft.com or http://www.bing.com. If those fail, fix the Windows network first (see Fix network connection issues in Windows in the referenced article).

2. Check for oversized messages blocking the Outbox

• In classic Outlook, open the Outbox folder.
• If there are stuck messages (especially older ones) with large attachments (around or above 20 MB):
  • Open the oldest stuck message.
  • Remove the large attachment, or replace it with a link to the file.
  • Save and send again, or delete the message if not needed.
• After clearing the Outbox, try Send/Receive again.

3. Fix Gmail authorization for classic Outlook Recent changes to Gmail/Google sign‑in and Outlook’s handling of Gmail can cause exactly the “suddenly stopped working” behavior even when everything looks configured correctly.

A. If Outlook shows IMAP/connection errors for Gmail Typical errors include:

• “We couldn’t log on to the incoming (POP/IMAP) server. Please check your email address and password and try again.”
• “We weren’t able to set up your Google account with IMAP. You may need to make changes to your Gmail settings.”
• Or Send/Receive error 0x800CCC0E for Gmail.

Then do the following for each Gmail account:

1. Make sure IMAP is enabled in Gmail

• In a web browser, sign in to Gmail for the affected account.
• Follow Google’s guidance in Add Gmail to another email client to confirm IMAP is enabled (Google is phasing out this switch, but if it is present, it must be on).

2. Re‑grant Outlook’s access during sign‑in If the account was added using modern OAuth sign‑in and stopped working:

• Ensure classic Outlook is updated to a build that includes the Gmail fixes:
  • For sign‑in issues: Current Channel Version 2404 (Build 17531.10000) or later.
  • For the Gmail permission issue: Current Channel Version 2412 (Build 18324.20168) or later.
• In Outlook, remove the broken Gmail account from File → Account Settings → Account Settings….
• Add the Gmail account again.
• When the Google sign‑in page opens in the browser, on the consent screen make sure the permission is checked for:
  • “Read, compose, send, and permanently delete all your email from Gmail.”
• Complete sign‑in. If Outlook shows a Retry link in an error dialog, use that to repeat the browser sign‑in and this time ensure that permission is selected.

If already on the fixed build and the Retry flow still fails, follow the manual workaround from the same article (re‑adding the account via Control Panel → Mail, or using IMAP with correct settings and app password if applicable).

B. If classic Outlook never prompts for a password when adding Gmail

• On the IMAP details page for the Gmail account in Outlook, ensure Require logon using Secure Password Authentication (SPA) is unchecked.
• If that still fails:
  1. Open Control Panel → Mail.
  2. Click Email Accounts… → New.
  3. Enter name, full Gmail address, and password (or Google app password if using that method), then Next and follow the prompts until setup completes.

4. Verify the correct app password type From the Q&A context, one user’s Gmail stopped working in classic Outlook because an incorrect app password type was used:

• They had configured Outlook with a Microsoft app password instead of a Google app password.
• After replacing it with a Google app password generated in the Google account’s security settings, classic Outlook started working again.

So for each Gmail account:

• If using app passwords, confirm the password in Outlook is a Google app password created under that Gmail account’s security settings, not any Microsoft‑generated password.
• Update the account in File → Account Settings → Account Settings… → select the Gmail account → Change and enter the correct Google app password.

If these steps are followed in order—online status, network, Outbox size, Gmail IMAP enabled, Outlook updated to a fixed build, correct Google consent box checked, SPA disabled, and correct Google app password—classic Outlook should resume sending and receiving Gmail.

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References:

• I can't send or receive messages in Outlook
• Unable to add a Gmail account to classic Outlook
• Unable to sign in or add a Gmail account to classic Outlook
• Troubleshoot Outlook email setup
• gmail accounts no longer working in outlook classic - Microsoft Q&A
• search for solutions another user has found - Microsoft Q&A