Since upgrading my MacBook Pro to macOS Tahoe 26.2, my Outlook for Mac application is no longer sending emails - how do I solve this?

Hi all,

I’m seeing exactly the same issue that Simon described.

We have multiple users reporting this problem, and I was also able to reproduce it myself. The issue appears to affect Outlook for Mac (new interface) on devices that have been upgraded to macOS version 26.2.

What happens is that Outlook suddenly stops sending and receiving emails. In the new Outlook interface, there is no longer an error or sync status page (it seems Microsoft removed it), so there’s no visibility into whether Outlook is connected to the server or what might be causing the sync failure. As a result, emails simply stop downloading or sending without any error messages.

I’ve tested installing the latest Outlook updates, including beta versions, but that did not resolve the issue. The only reliable workaround so far has been switching back to legacy Outlook, which works without any problems. However, once switching back to the new Outlook interface, the issue immediately returns.

Occasionally, Outlook will start working again on its own for a short period, then stop again without any warning or error message.

Based on all of this, it strongly appears to be a compatibility issue between the latest macOS version (26.2) and the new Outlook for Mac. This seems like something that will need to be addressed and patched by Microsoft.

If anyone from Microsoft or someone with deeper insight has guidance or updates on this issue, it would be greatly appreciated.

I think I may have found a durable fix.

On macOS Tahoe 26.2, make sure you’re running the latest Microsoft AutoUpdate and that AutoUpdate is allowed to launch at login (so it can run in the background). After enabling that, AutoUpdate was able to update Outlook properly, and sending/receiving started working again.

My working assumption is that my Outlook build wasn’t actually the latest (even though it looked up to date), and AutoUpdate wasn’t running reliably after the OS upgrade.

Hello,

You have already tried removing and re-adding the account without success, so please check if this is specific to the interface version you are running.

• In your Outlook window, usually near the top right corner, do you see a toggle switch labeled New Outlook, and if so, is it currently turned on or off?
• Also, if you check the Sync Errors log found under the Window menu at the top, is there a specific error code listed for the stuck emails?

If your Outlook for Mac is not sending emails after upgrading to macOS Tahoe 26.2, here are some steps you can take to troubleshoot the issue:

1. Check for Software Updates: Ensure that both your macOS and Outlook for Mac are up to date. Running outdated software can lead to compatibility issues.
2. Check Folder Hierarchy: Sometimes, the folder hierarchy in your mailbox can become corrupted, which may prevent emails from being sent. Make sure that your Sent Items folder is correctly configured and not mistakenly converted into another folder like Archive.
3. Run Microsoft 365 Diagnostics: If you have access to a Microsoft 365 administrator account, you can run diagnostics to check for connectivity issues and get possible solutions.
4. Remove and Re-add Account: Since you've already tried removing and re-adding your account, ensure that you are entering the correct server settings for your hotmail.com email address.
5. Check for Service Issues: If other users in your organization are experiencing similar issues, it may be a service problem. Check the Microsoft 365 Service health status for any ongoing issues.
6. Clear Local State: You can try resetting the new Outlook by using the command olk.exe --clearLocalState. This may help in resolving any local issues with the application.

If these steps do not resolve the issue, consider reaching out to Microsoft support for further assistance.

References:

• Email messages are stuck in Outbox in Outlook 2016 for Mac
• Fix Outlook connection problems for Microsoft 365 account