SMTP looks exactly like this
$ telnet/port=25 arizona.edu
Trying... Connected to ARIZONA.EDU.
220 Arizona.EDU -- Server ESMTP (PMDF V4.3-10 #2381)
250 Arizona.EDU OK, Tennis.Opus1.COM.
354 Enter mail, end with a single ".".
This is where all the rest of the headers go ...
221 Bye received. Goodbye.