Popular antivirus software, AVG Internet Security, AVG Free, and Avast, published an update at the beginning of August which has caused many users email to stop being sent.
By default AVG/Avast injects a signature into users email including a mail icon with a broken link which causes the HostAway SMTP server to reject the message (as well as many other provider’s SMTP servers).
To correct this simply disable the AVG/Avast signature using the steps below:
Open AVG/Avast dashboard > select Menu > Settings > Basic protection > Email shield > Disable signature
The steps to disable the signature vary slightly between AVG and Avast, please refer to their support articles for more detailed steps: