The IPaddr where the Postfix has been installed is 10.83.23.220.
I've connected with telnet from different VM and got the result:
telnet 10.83.23.220 25
Connected to 10.83.23.220.
Escape character is '^]'.
220 centos7-1.localdomain ESMTP Postfix
It's completely different from the lab guide. Is Ok?
According to the lab guide, it needs to be checked with mutt or mail. How to check with mail ? What should I see ?