Fix Outlook ‘Not Implemented’ Error on Send/Receive

This guide walks you through resolving the Outlook “Not Implemented” error that appears during manual or automatic send/receive. The error usually points to a broken add-in, a corrupted profile, or an outdated Office installation. You’ll fix it by disabling add-ins, repairing Office, and rebuilding the mail profile if needed.

What You’ll Need

Administrator access to your Windows computer (to run repairs and modify registry keys if necessary).
Your Outlook password (to re-add your email account after rebuilding the profile).
Access to your email provider’s server settings (IMAP/POP/SMTP) if you set up the account manually.

Step-by-Step

Close Outlook completely. Make sure no background processes are running. Press Ctrl+Shift+Esc to open Task Manager, look for “Outlook” under Processes, select it, and click “End Task.”
Start Outlook in Safe Mode. Press Win+R, type outlook.exe /safe, and press Enter. If Outlook opens without the error, an add-in is the culprit.
Disable add-ins. In Safe Mode, go to File > Options > Add-ins. At the bottom, next to “Manage,” select “COM Add-ins” and click “Go.” Uncheck every add-in (especially third-party ones like CRM, antivirus, or PDF tools) and click OK. Restart Outlook normally and test send/receive.
If the error persists, run Office Repair. Close Outlook. Go to Control Panel > Programs > Programs and Features. Find Microsoft Office (or Microsoft 365) in the list, select it, and click “Change.” Choose “Quick Repair” first. If that doesn’t help, repeat with “Online Repair” (requires internet and may take 15–30 minutes).
Check for Windows and Office updates. Go to Settings > Update & Security > Windows Update and install pending updates. Also open any Office app, go to File > Account > Update Options > Update Now.
Create a new Outlook profile. Open Control Panel > Mail (search “Mail” in the Start menu). Click “Show Profiles,” then “Add.” Give it a name (e.g., “NewProfile”), enter your email, and follow the prompts. After creation, select “Always use this profile” and choose the new one. Restart Outlook.
If the error still appears, delete the old profile. In the same Mail settings, select the old profile and click “Remove.” Confirm, then restart Outlook.
Repair the Outlook data file. Close Outlook. Open Run (Win+R) and type scanpst.exe (or find it in C:\Program Files\Microsoft Office\root\Office16\). Browse to your .pst or .ost file (usually in %LocalAppData%\Microsoft\Outlook), select it, and click “Start.” Let it repair any errors.
As a last resort, reset the Outlook navigation pane. Close Outlook. In Run, type outlook.exe /resetnavpane and press Enter. This resets the folder list but does not delete emails.

Common Mistakes

Skipping Safe Mode. If you don’t test in Safe Mode first, you might waste time repairing Office when the issue is a single add-in.
Not closing Outlook before repairing. Office repair will fail or be incomplete if Outlook is still running in the background.
Deleting the profile without backing up. Your emails are usually still on the server, but local folders, rules, and signatures may be lost. Export to a .pst first if you have custom folders.
Using the wrong scanpst.exe path. The tool location varies by Office version and bitness. Use the search function in File Explorer to find it.

Tips

Disable hardware graphics acceleration. In Outlook, go to File > Options > Advanced. Under “Display,” check “Disable hardware graphics acceleration.” This resolves some rendering errors that appear during send/receive.
Create a new Windows user profile if the error follows you across all Office apps—it may be a corrupted user account.
Keep your antivirus from scanning Outlook data files. Add the .ost/.pst file extensions to the exclusion list in your antivirus settings. Real-time scanning can interfere with send/receive.

Troubleshooting

If the error persists after all steps:

Check if the error occurs only with a specific email account. In Outlook, go to Send/Receive > Send/Receive Groups > Define Send/Receive Groups. Uncheck all but one account and test each individually. If only one account fails, remove and re-add that account.
Look for a corrupted form or template. The “Not Implemented” error can be triggered by a custom form. Go to File > Options > Advanced, click “Custom Forms,” then “Manage Forms.” Set the cache to “Clear” and restart Outlook.
Try a different mail protocol. If you use IMAP, switch to POP3 (or vice versa) temporarily to see if the error is protocol-specific.
Use the Microsoft Support and Recovery Assistant (SaRA). Download and run the tool from Microsoft’s official site. It can automatically diagnose and fix Outlook configuration issues.

Frequently Asked Questions

Will I lose my emails if I create a new profile?

No. Your emails are stored on the mail server (or in a .pst file). When you re-add the account, Outlook will download them again. Local folders and rules may need to be recreated.

Why does the error only happen on manual send/receive?

Manual send/receive triggers a full synchronization of all folders, which can expose corrupted items or add-in conflicts that automatic intervals might skip.

Can this error be caused by a large mailbox?

Yes, an oversized .ost file (over 50 GB) can cause various sync errors. Archive old emails to reduce the mailbox size.

Is there a registry fix for this error?

Some users report success by deleting the HKCU\Software\Microsoft\Office\16.0\Outlook\Profiles key, but this is a drastic step that removes all profiles. Only do this after backing up your data and with expert guidance.

Does this error affect Outlook on Mac?

No, this error is specific to Outlook for Windows. Mac users with similar issues should check for add-ins and update the app.

How long does the Online Repair take?

It can take 15 to 30 minutes depending on your internet speed and Office installation size. Your computer may restart during the process.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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