The original message was received at Wed, 23 Sep 2015 14:54:37 +0530 from 67.248.226.137 ----- The following addresses had permanent fatal errors ----- <dev at openvswitch.org> ----- Transcript of session follows ----- ... while talking to openvswitch.org.: 550 5.1.2 <dev at openvswitch.org>... Host unknown (Name server: host not found)