Using this feature requires use of the optional Cloud Protection Layer (CPL) with the Barracuda Email Security Gateway.
Many users subscribe to websites and lists and later forget that they subscribed, or subscribed unknowingly. Email messages containing anything that looks like an unsubscribe link or instruction may or may not be considered spam by the recipient. You can choose to block these bulk email messages, thereby reducing the load on your mail server. Configure Bulk Email Detection on the INBOUND SETTINGS > Anti-Spam/Antivirus page of your CPL.
To allow all such emails that are not otherwise detected as spam, set this feature to Off.