I have a vps with Centos 6.5 and postfix installed. When I want to connect to a smtp server like google or mail gun, I get the error
502 command not implemented. Can anybody help me please?
This is the full story:
[root@mail ~]# telnet smtp.gmail.com 25 Trying 18.104.22.168... Connected to smtp.gmail.com. Escape character is '^]'. 220 smtp.passthru HELO 250 smtp.passthru STARTTLS 502 Command not implemented
I think the problem is "smtp.passthru" ... What is that?!