# telnet localhost 110
Trying 127.0.0.1...
Connected to localhost.
Escape character is ''^]''.
+OK <2569.1057661928@mail.xpr.org>
user am3n
+OK
pass mys3cr3t
+OK
quit
+OK
Connection closed by foreign host.

                                  
below is the example on how test connection to smtp server

# telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is ''^]''.
220 mail.xpr.org ESMTP
mail from: imran@xpr.org
250 ok
rcpt to: am3n@xpr.org
250 ok
data
354 go ahead
Subject: Testing first time
test test
.
250 ok 1103635217 qp 16177
quit
221 mail.xpr.org
Connection closed by foreign host.