Many of our client here in Qatar having issues sending mail to some organization like QP , Qatar Petrolium through Barracuda. Please see the resolution here. Permanent solution Upgrade to Firmware Version 6.X ‘This is issue has been addressed on that Version 6.1.5.008 Fix: Resolved issue with connecting to recipient servers when Enable SMTP over TLS/SSL is enabled (see the ADVANCED > Email Protocol page). Temporary solutions Advanced > Email Protocol and at the bottom change “Enable SMTP over TLS/SSL” to NO.
