Zen and the Art of Internet | Page 7

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 [email protected] Sat May 25 17:06:01 1991 Received: from hq.mil by house.gov with SMTP id AA21901 (4.1/SMI for [email protected]); Sat, 25 May 91 17:05:56 -0400 Date: Sat, 25 May 91 17:05:56 -0400 From: The President Message-Id: <[email protected]> To: [email protected] Subject: Meeting
Hi Dan .. we have a meeting at 9:30 a.m. with the Joint Chiefs. Please don't oversleep this time.
The first line, with From and the two lines for Received: are usually not very interesting. They give the ``real'' address that the mail is coming from (as opposed to the address you should reply to, which may look much different), and what places the mail went through to get to you. Over the Internet, there is always at least one Received: header and usually no more than four or five. When a message is sent using UUCP, one Received: header is added for each system that the mail passes through. This can often result in more than a dozen Received: headers. While they help with dissecting problems in mail delivery, odds are the average user will never want to see them. Most mail programs will filter out this kind of ``cruft'' in a header.
The Date: header contains the date and time the message was sent. Likewise, the ``good'' address (as opposed to ``real'' address) is laid out in the From: header. Sometimes it won't include the full name of the person (in this case The President), and may look different, but it should always contain an email address of some form.
The Message-ID: of a message is intended mainly for tracing mail routing, and is rarely of interest to normal users. Every Message-ID: is guaranteed to be unique.
To: lists the email address (or addresses) of the recipients of the message. There may be a Cc: header, listing additional addresses. Finally, a brief subject for the message goes in the Subject: header.
The exact order of a message's headers may vary from system to system, but it will always include these fundamental headers that are vital to proper delivery.
Bounced Mail
When an email address is incorrect in some way (the system's name is wrong, the domain doesn't exist, whatever), the mail system will bounce the message back to the sender, much the same way that the Postal Service does when you send a letter to a bad street address. The message will include the reason for the bounce; a common error is addressing mail to an account name that doesn't exist. For example, writing to Lisa Simpson at Widener University's Computer Science department will fail, because she doesn't have an account. {Though if she asked, we'd certainly give her one.}
From: Mail Delivery Subsystem Date: Sat, 25 May 91 16:45:14 -0400 To: [email protected] Cc: [email protected] Subject: Returned mail: User unknown
----- Transcript of session follows ----- While talking to cs.widener.edu: >>> RCPT To: <<< 550 ... User unknown 550 lsimpson... User unknown
As you can see, a carbon copy of the message (the Cc: header entry) was sent to the postmaster of Widener's CS department. The Postmaster is responsible for maintaining a reliable mail system on his system. Usually postmasters at sites will attempt to aid you in getting your mail where it's supposed to go. If a typing error was made, then try re-sending the message. If you're sure that the address is correct, contact the postmaster of the site directly and ask him how to properly address it.
The message also includes the text of the mail, so you don't have to retype everything you wrote.
----- Unsent message follows ----- Received: by cs.widener.edu id AA06528; Sat, 25 May 91 16:45:14 -0400 Date: Sat, 25 May 91 16:45:14 -0400 From: Matt Groening Message-Id: <[email protected]> To: [email protected] Subject: Scripting your future episodes Reply-To: [email protected]
.... verbiage ...
The full text of the message is returned intact, including any headers that were added. This can be cut out with an editor and fed right back into the mail system with a proper address, making redelivery a relatively painless process.
Mailing Lists
People that share common interests are inclined to discuss their hobby or interest at every available opportunity. One modern way to aid in this exchange of information is by using a mailing list---usually an email address that redistributes all mail sent to it back out to a list of addresses. For example, the Sun Managers mailing list (of interest to people that administer computers manufactured by Sun) has the address [email protected]. Any mail sent to that address will ``explode'' out to each person named in a file maintained on a computer at Northwestern University.
Administrative tasks (sometimes referred to as administrivia) are often handled through other addresses, typically with the suffix -request. To continue the above, a request