Avast file shield blocks my outgoing mail on Thunderbird

Avast file shield is blocking my outgoing mail on Mozilla Thunderbird. I have to disable the file shield before my emails can be sent. This is very irritating and is making me consider alternative antivirus software.
I have updated both Avast and Thunderbird and problem persists.

Is there a setting change or workaround for this problem?

The file shield shouldn’t have anything to do with sending email.

The Mail Shield as its name implies handles mail scanning, so I’m at a bit of a loss as to what this is and why disabling the file system shield resolves it.

Can you post a screenshot of any error/message window.