In our group we are using suse and Postfix SMTP server. Every thing was fine until last month when we restart our mail server and also firewall. The first problem is that when we use Thunderbird with security and Authentication it is impossible to send a email. we receive this error “Unable to authentication to SMTP server mx.mydomain. The server does not support any compatible secure authentication mechanism but you have chosen secure authentication. Try switching off secure authentication”. however , it is possible to send email without Authentication in local network. The second problem is that we can not send email via Thunderbird from outside of our local network. The error is “Mail server responded 5.7.1 < x...@y.com> relay access denied. Please check the message recipient x...@y.com and try again”. we also have web mail (Squirrelmail) and it works without any problems everywhere. I completely confuse without change anything these problem happen. I was wondering if someone could help me.
