What: New feature to Force TLS for inbound mail
To require mail coming inbound to Email Gateway Defense to use a TLS connection, use the SMTP Encryption section on the Domains > Edit Settings page for each domain.

Use the Require TLS to Barracuda from these domains list to require a TLS connection from certain domains to Barracuda. You can manually add specific domains one at a time or use the Bulk Edit button.

Note: TLS provides secure transmission of email content, both inbound and outbound, over an encrypted channel using the Secure Sockets Layer (SSL). If a TLS connection cannot be established, then the mail will not be delivered.