thufir@dur:~$
thufir@dur:~$ telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 dur.bounceme.net ESMTP Postfix (Ubuntu)
helo me
250 dur.bounceme.net
mail from:[email protected]
250 2.1.0 Ok
rcpt to:thufir@localhost
451 4.3.0 <[email protected]>: Temporary lookup failure
quit
221 2.0.0 Bye
Connection closed by foreign host.
thufir@dur:~$