By Danny Green, Staff Writer, d.green7@genie.com
This month I will cover E-Mail.
E-mail is useful in the same way as the postal system (snail mail), only faster. First, I want to cover the way in which E-mail addresses work. My E-mail address is D.Green7@Genie.com. This means that I have an account called D.Green7; the "@", called a commercial "at" sign, means the account is "at" the domain called Genie.com.
I will digress a bit to explain domain names. A domain name is usually made up of several sub-domain names that, when added up, form a unique name on the internet. In an earlier article I referred to a fictional University called M.D. University. Lets give MDU a fictional Internet address, MDU.edu. Lets say I want to send a message to the pathology department at MDU. The computer in the pathology dept. is called "cadaver". Lets further say that I want to send a letter to Dr. Malcolm Killdare in that department, and his E-mail address is M.Killdare. His full E-mail address would be M.Killdare@cadaver.MDU.edu. This means that M.killdare has an account at the computer named cadaver at MDU. All three parts, cadaver, MDU, and edu, are called sub-domains. These sub-domains are written left to right. "Edu" (also referred to as the "top level domain") is used for educational institutions. The next one is MDU. This is the name of the institution. And finally, cadaver tells us which computer we want at MDU. There are several types of "top level domains". Two of the most common are edu = education, and com = commercial.
OK, back to the E-mail. Consider this E-mail I received in early January. It is from National Amiga:
INTERNET# Document Id: UX012.BUX0115762
Item 5567875 97/01/02 15:25
From: NACBOT@MAIL.NATIONALAMIGA.COM@INTERNET#
To: D.GREEN7 Daniel W. Green
Sub: National Amiga Technical Infor
From nacbot@mail.nationalamiga.com Fri Jan 3 01:26:13 1997
Received: by (genie.)relay1.geis.com (for INTERNET#)
( p822/1.32 ) ; Fri, 3 Jan 97 01:30:05 GMT
Received: from firewall.genie.net (firewall.GEnie.net [204.176.7.2]) by relay1.
geis.com (8.7.6/8.7.3) with SMTP id BAA09022 for <D.Green7@genie.geis.com>;
Fri, 3 Jan 1997 01:26:12 GMT
Received: from mail.nationalamiga.com (isdn2.wwdc.com [199.45.70.94]) by
firewall.genie.net (8.6.12/8.6.12) with SMTP id UAA10131 for
<D.Green7@Genie.
Com>;
Thu, 2 Jan 1997 20:27:27 -0500
Received: by mail.nationalamiga.com (Interworks_SMTPpost 8.100 June 5,
1996)
id AA01; Thu, 2 Jan 1997 20:24:46 -5
Received: by mail.nationalamiga.com (Interworks_SMTPpost 8.100 June 5,
1996)
id AA01; Thu, 2 Jan 1997 20:20:04 -5
From: nacbot@mail.nationalamiga.com (National Amiga Canada Bot)
To: D.Green7@genie.geis.com
Subject: National Amiga Technical Information
Date: Thu, 2 Jan 1997 20:20:04 -5
Organization: National Amiga
Message-ID: <19970102.89C1CA8.11EE3@mail.nationalamiga.com>
addupdatelist @..com
=END=
That is a lot of junk (technical term), just to get the message, "addupdatelist @..com". The "junk" as I have referred to it is called the Header. Mail messages are divided into two parts: the header, and the body. In this case the body consists of "addupdatelist @..com". Everything else is header. The first line of the header will always start with the word "From" (except, of course, as in this instance in which Genie appends a line or two to the top). (now you know why I don't usually make blanket statements :)). This line will give you the address from where the message came (makes sense, right?). In this case, it is from NACBOT@MAIL.NATIONALAMIGA.COM@INTERNET# (nice folks, by the way). The "@internet" appended to the top level domain is a local gateway. The rest of the lines are not always there, and if they are, they are not always in this order. At a minimum you should always see the "From", "Date" and "Subject" lines. In this case the Initial "From" line is followed by about 20 lines of technical information. Most of this stuff is unimportant to you. I will cover some of it here so that if you should need to know, you will understand it.
You will note that there are several "Received by" statements. This is the path this message took to get to me. It lists the times, dates and programs that handled the message. Take a look at the last "Received by" statement. This is the time and date the message got to this location. Notice the time is "Date: Thu, 2 Jan 1997 20:20:04 -5". The time is given in twenty-four hour clock time (also referred to as "military time"). Subtract twelve from twenty to get 8 pm. But what about the -5, you might ask? Good question. Suppose the message was from California. Is it 8 pm here or 8pm in California? Because of that question, the time is given in Greenwich Mean Time (GMT), also known as Universal Time (UT). Greenwich is in Great Britain. Greenwich has been established as the "Official" time for most of the world. Time zones are designated from there. NJ is five hours "behind" Greenwich. If it is 8 pm in Greenwich, it is 3 pm in NJ. The -5 tells us that the message was sent -5 hours from GMT, so it's 8pm -5 hours is 3 pm local time.
Well, that's it for this month. I hope it was useful.
______ DannyG________////____ | __ \ Crew-Dog KC-10A aka: D.Green7@Genie.Com | | \ \ ____Raven__ __ ============////====== | | ) )(___ \ ( \ | ) Amiga 2500 //// OS 3.1 | |__/ / / __ \| \| | \\\\//// |______/ (_______(__|\____) \\\///