Troubleshoot Outlook “Not implemented” Unable to Send Email Error


After upgrading my workstation to Windows 10 Insider Preview build 17046 my Outlook 2013 stopped working. Specifically, Outlook was unable to send emails, Send/Receive All Folders, or launch Account Settings. Outlook will prompt for an error message saying “Not implemented” with no additional information was given. The irony is the error message prompt also asks “Was this information helpful?”

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Send/Receive All Folders cause Not implemented.

This guide will help you troubleshoot and fix Microsoft Outlook showing “not implemented” error.

Check other Office Program

If you have issues with Microsoft Outlook right after the upgrade it’s worthwhile to check if other Office applications work or not. Try to launch Word, PowerPoint or Excel see if those apps run without any error, primary check the validity of office license is still valid. In my case, when I try to launch other Microsoft office applications, it too showed abnormal behavior. If this happened to you, try repair or reinstall Microsoft Office.

To repair, go to Settings > Apps & features > find Microsoft Office (your version) Professional Plus 2013. Select the item and click “Modify”

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This will cause the installer to launch, choose Repair and Continue to finish.

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Try Recreate Outlook.OST file

There are different methods to recreate your Outlook OST file. Worse case and the simplest case is to make a backup and remove the existing file. You can find your OST file under the path below.


The reason I recommend this approach is that often times there is no method to recreate through UI while Outlook doesn’t respond or in a corrupt state. Assuming you are using exchange and IMAP, all the mail are also stored on the server so by deleting the OST file you won’t lose any emails. What you will lose are some of the local rules, or folders you have since created. Below is an example where I’m not able to access “Account Settings”, not to mention initiate a self-repair cycle within Outlook.

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You will find errors as follows:

Metered Connection Warning

We noticed the metered connection you’re on may charge extra and this Office program might access online content. You may want to:

  • Tap or click the network icon and turn on Airplane mode to go offline
  • Connect to a Wi-Fi or LAN network that isn’t metered
  • Check the status of your data plan with your mobile operator

Upgrade in Progress

Your mailbox is currently being optimized as part of upgrading to Outlook 2013. This one-time process may take more than 15 minutes and performance may be affected while the optimization is in progress.

None of those messages above actually helps to diagnose what actually happened nor they offered any advice to fix the issue. So if this happened to you, try one of the two tips above and hopefully, your Outlook will go back and function as normal again.



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