Connectivity Issue with Outlook

Issue:

Outlook Classic email synchronization issue.

Error Code: 0x800CCC0E

Message: Outlook cannot synchronize subscribed folders… Cannot connect to the server.

Troubleshooting Steps Performed:

Outlook repair completed

Created a new Outlook profile

Deleted and recreated the OST file

Reinstalled Microsoft Office

Removed and re-added the email account

Removed and recreated the Outlook data file

Checked registry path (HKEY_CURRENT_USER → Microsoft Office → Identity)

Verified Gmail security settings (App password, backup codes, and 2-step verification)

Observation:

The issue was not resolved with the above steps in the existing Windows user profile.

Temporary Resolution:

Created a new Windows user account and configured Outlook.

Email synchronization is working properly in the new profile.

Note:

Creating a new Windows user profile is not a feasible solution for all users.

We are currently checking for a permanent solution from Microsoft support

Hi @Mataio Irving,

Welcome to the Microsoft Q&A forum.

I would like to provide you with the following information:

To resolve this issue, please follow the steps below:

1/ Check the Outlook status

Please look at the bottom-right corner of Outlook and check the current status.

If it shows Disconnected, Working Offline, or Trying to connect…, this means that Outlook is unable to connect to the email server to send your messages.

To resolve this, please do the following:

• Step 1: Select Send/Receive
• Step 2: Check whether Outlook is currently in Work Offline mode. If so, please turn it off.

Additionally, you can try enabling Work Offline and then disabling it again to see if the issue is resolved.

2/ Check for emails with large attachments

Some email providers (such as your ISP or Gmail) do not allow sending emails that exceed a certain size limit. Adding large images or attachments may prevent emails from being sent (and can also affect subsequent emails).

Please follow these steps:

• Open the Outbox
• Open the stuck email, starting with the oldest one
• If the email contains an attachment larger than 20 MB, remove the attachment and:
  • Attach a smaller file, or
  • Attach a link to the file

For more information, please refer to Reduce attachment size to send large files with Outlook.

3/ Perform an Online Repair for Outlook (Classic)

• Step 1: Press Windows + I
• Step 2: Select Apps > Installed apps
• Step 3: Locate Microsoft Office
• Step 4: Select the … icon > Modify > Online Repair

4/ Create a new Outlook profile

• Step 1: Open Control Panel
• Step 2: Select Mail (Microsoft Outlook)
• Step 3: Select Show Profiles
• Step 4: Select Add to create a new profile
  • Step 5: Return to Show Profiles, select the newly created profile, and choose Always use this profile

5/ Open Outlook in Safe Mode

Please open Outlook in Safe Mode to check whether the issue still occurs.

If Outlook works normally in Safe Mode, the issue is most likely caused by one of the add-ins.

Next, open Outlook in normal mode and follow these steps:

• Step 1: Select File > Options
• Step 2: Select Add-ins > Go
• Step 3: Disable all add-ins, then re-enable them one by one to identify which add-in is causing the issue

You can refer to the document below for more information:

I can't send or receive messages in Outlook - Microsoft Support

I hope this information is helpful. Please follow these steps and let me know if it works for you. If not, we can work together to resolve this.   

Thank you for your patience and your understanding. If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.

I look forward to continuing the conversation.

 If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". 

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread. 

Use the following checks in classic Outlook for Windows to restore send/receive and the Google connection:

1. Check Outlook’s connection status

• 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.
• Go to the Send/Receive tab on the ribbon.
• In the Preferences group, select Work Offline once to toggle it back online.
• After it reconnects, select Send/Receive to force a sync and test sending/receiving.

2. Confirm Internet connectivity

• Open a browser (Microsoft Edge or Google Chrome).
• Browse to http://www.microsoft.com or http://www.bing.com.
• If these sites do not load, fix the PC’s network first using the guidance in Fix network connection issues in Windows. Outlook will not work until the device is online.

3. Check for large or stuck messages

• In Outlook, open the Outbox folder.
• Look for messages that are still there, especially with large attachments (over ~20 MB).
• Open the oldest stuck message, remove large attachments, or replace them with a link, then send again.
• After clearing the Outbox, use Send/Receive to test.

4. Manually trigger sync

• In classic Outlook, go to the View tab on the ribbon.
• Select the Sync button to manually check for new mail and send pending messages.
• Watch the status message at the bottom of the message list to confirm syncing is running. For more detail, see Sync to manually check for new mail and to send messages in Outlook.

5. If errors persist, repair the Outlook data file If Outlook shows connection-related error codes like 0x80042109, 0x8004210a, 0x800ccc0e, etc., run the Inbox Repair Tool:

• Follow Repair Outlook data files (.pst and .ost) to repair the Personal Folders File (.pst) used by classic Outlook.
• This typically takes about 15 minutes.
• After repair, restart Outlook and test send/receive again.

If, after these steps, Outlook still cannot send/receive or connect to Google, involve the company’s IT admin to verify account configuration, any recent policy changes, and whether Google/SMTP access has been restricted at the tenant or firewall level.

References:

• I can't send or receive messages in Outlook