[root@devel3 root]# telnet perlmonk.org 25
Trying 199.5.193.8...
Connected to perlmonk.org.
Escape character is '^]'.
220 perlmonk.org ESMTP Exim 3.36 #1 Mon, 04 Oct 2004 19:35:40 -0400
HELO devel3.xxx.org
250-perlmonk.org Hello devel3.xxx.org [64.xxx.xxx.xxx]
250-SIZE
250-PIPELINING
250 HELP
MAIL FROM: tachyon@perlmonk.org
250 <tachyon@perlmonk.org> is syntactically correct
RCPT TO: tachyon@perlmonk.org
250 <tachyon@perlmonk.org> is syntactically correct
DATA
354 Enter message, ending with "." on a line by itself
Hello me,

Telnet (the program, not the protocol/server) can be used 
to do all sorts of cool stuff. Try telnet perlmonks.org 80
and then type: "GET / HTTP/1.0\n\n" no quotes \n == [ENTER]

To pick up your email via POP3 you telnet pop3server 110 then:
USER username
PASS password
LIST
RETR n
QUIT

Bye for now
.
250 OK id=1CEcPR-0000yC-00
QUIT
221 perlmonk.org closing connection
Connection closed by foreign host.
[root@devel3 root]#