Redditor, tdark12 has made a full thread on Redditor describing the issue and give a solution for disabling the same. He noted that Avast is adding an unseen signature in his emails. As stated above, the settings for the signature have also been added to the Web Shield without any way of disabling it. So, even though you DON’T have Mail Shield installed, it could still be appending the signature. tdark12 says that the solution of installing the Mail Shield, disabling the clean message, and uninstalling the Mail Shield did not work for him so he found out another way to disable this unseen footer. To disable the automatic email signature:
Go to the directory of your Avast! installation. Typically, this is C:\ProgramData\AVAST Software\Avast\EmailShield.ini. Copy the EmailShield.ini file to the Desktop. Edit the following values (or set everything with a 1 to 0 if you don’t use the Mail Shield):
[EmailScanner] InsertNoteCleanMsgOut=0 InsertNoteCleanMsgIn=0 InsertNoteInfectedMsgIn=0
Turn off the Avast! Self-Defense Module (located at Settings > Troubleshooting > Enable Avast self-defense module) Copy the edited EmailShield.ini file into the same directory you pulled it from. Confirm administrative permissions. Restart your computer.
Alternatively, you can open an elevated instance of Notepad to edit the .ini file to avoid all the copy-pasting and disabling of the Self-Defense module. Make sure to restart.
