Avast Email Hijacking in Firefox: Fix

TL;DR

Avast can sometimes interfere with email sending in Firefox by injecting tracking code into the content. This guide shows you how to disable this feature and restore normal email functionality.

Solution Guide

1. Understand the Problem
   • Avast’s ‘Email Protection’ feature can scan outgoing emails for threats, but it sometimes incorrectly modifies email content.
   • This is most noticeable when sending emails through webmail clients like Gmail or Outlook.com within Firefox.
   • The injected code isn’t malicious, but it can cause formatting issues or trigger security warnings in some cases.
2. Disable Email Protection in Avast
   1. Open the Avast user interface.
   2. Click on ‘Protection’ in the main menu.
   3. Select ‘Email Protection’.
   4. Toggle the switch to turn ‘Email Protection’ OFF. You may be prompted for confirmation; confirm that you want to disable it.
3. Check Firefox Add-ons (Just in Case)

   Although less common, a conflicting add-on could also cause issues.

   1. In Firefox, type about:addons into the address bar and press Enter.
   2. Review your installed extensions/add-ons. Disable any recently added or suspicious ones to see if it resolves the problem.
4. Clear Firefox Cache

   Clearing the cache can remove any lingering modified data.

   1. In Firefox, press Ctrl+Shift+Delete (or Cmd+Shift+Delete on macOS).
   2. Select ‘Cache Web Content’.
   3. Click ‘Clear Now’.
5. Restart Firefox

   Completely close and restart Firefox to ensure the changes take effect.

6. Test Email Sending

   Send a test email through your webmail client (e.g., Gmail, Outlook.com) to confirm that the content is no longer being modified.

7. Re-enable Avast Protection (Optional)

   If disabling Email Protection fixes the issue, you can try selectively re-enabling other Avast features one by one to identify if a specific component is causing the conflict. However, be aware that this may bring back the email hijacking behaviour.