The next time the author checked his mail, he would see it listed in his mailbox as:
% mail "/usr/spool/mail/brendan": 1 messages 1 new 1 unread U 1 joeuser@foo.widene Tue May 5 20:36 29/956 print job's stuck ?
which gives information on the sender of the email, when it was sent, and the subject of the message. He would probably use the reply command of Unix mail to send this response:
? r
To: joeuser@@foo.widener.edu
Subject: Re: print job's stuck
You shouldn't print binary files like GIFs to a printer!
Brendan
Try sending yourself mail a few times, to get used to your system's mailer. It'll save a lot of wasted aspirin for both you and your system administrator.
Anatomy of a Mail Header
An electronic mail message has a specific structure to it that's common across every type of computer system. {The standard is written down in RFC-822. See also RFCs for more info on how to get copies of the various RFCs.} A sample would be:
>From bush@hq.mil Sat May 25 17:06:01 1991
Received: from hq.mil by house.gov with SMTP id AA21901
(4.1/SMI for dan@house.gov); Sat, 25 May 91 17:05:56 -0400
Date: Sat, 25 May 91 17:05:56 -0400
From: The President <bush@hq.mil>
Message-Id: <9105252105.AA06631@hq.mil>
To: dan@senate.gov
Subject: Meeting