Outlook Error: "One or more add-ins couldn't complete processing your email"

Issue Summary

When trying to send an email, Outlook displays the error message: "One or more add-ins couldn't complete processing your email." The message fails to send and is automatically moved to the Drafts folder.

Root Cause

This issue typically occurs when you navigate away from an email, switch windows, or close a compose window too quickly after clicking Send. Background add-ins (such as security, encryption, compliance, or digital signature tools) require uninterrupted time to process the message before it leaves your mailbox. If that process is interrupted, Outlook blocks the transmission to prevent unencrypted or non-compliant data from leaking.

Resolution Steps

Method 1: Resend the Stuck Message

  1. Navigate to your Drafts folder.
  2. Open the affected email.
  3. Click Send again.

Important: Stay completely focused on the email window and do not click away until the message fully disappears from the screen.

Method 2: Identify and Disable the Faulty Add-in

If this error happens frequently, a specific add-in may be hanging or crashing.

  1. In Outlook, click File in the top-left corner.
  2. Select Options, then click Add-ins.
  3. At the bottom of the window, look for the Manage dropdown menu, select COM Add-ins, and click Go...
  4. Uncheck the third-party add-in you suspect is causing the issue (e.g., encryption tools, security scanners, or CRM plugins).
  5. Click OK and restart Outlook.

Method 3: Troubleshoot in Safe Mode

To confirm if an add-in is the absolute root cause:

  1. Close Outlook completely.
  2. Press the Windows Key + R to open the Run dialog box.
  3. Type outlook.exe /safe and press Enter.
  4. Test sending an email. If the error does not appear, an add-in is definitely causing the conflict.

More Information

For additional assistance, please contact IT Support Services at 531-622-2900 or ITSupportServices@mccneb.edu.

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