telnet 127.0.0.1 1234
   
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
220 smtp.gmail.com ESMTP z19sm6017985wmi.7 - gsmtp
   
HELP
   
214 2.0.0 https://www.google.com/search? btnI&q=RFC+5321 z19sm6017985wmi.7 - gsmtp