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Email Addresses

Some notes on decipering Email addresses

To read an email address, read it from right to left, that is backwards.

Look at this ficticious email which has 3 parts P.Brannigan @ [can you figure why the address is non-contiguous?]

Every internet address has 3 parts - a user name (P.Brannigan), an at @ sign and the address of the user's mail server - in this case The mail server address is actually called the domain name and it is based on something called an IP (or Internet Protocol) address.

Each server connected to the Internet has a numerical IP address. The IP address is four sets of numbers connected with periods. The IP address for the reddwarf mail server is 143.117.XX.YY. Fortunately, the domain name system means you don't have to remember IP addresses. The domain name system associates the numerical IP address with an easier to remember "name". You may have to make use of the numerical IP addresses when using FTP or Telnet but IP addresses and domain names should work equally well in most cases.

Domain names are broken down as follows:

  • EDU - Educational sites in the U.S.
  • COM - Commercial sites in the U.S.
  • GOV - U.S. Government sites
  • NET - Network administrative organisations
  • MIL - U.S. military sites
  • ORG - U.S. organisations that don't fit into other categories
  • SU - Soviet Union - still used despite the none existence of same!
  • UK - United Kingdom
  • IE - Ireland
  • FR - France
  • CA - Canada

The rest of the REDDWARF.QUB.AC.UK domain name lists the "subdomains" that tell you where the mail server is actually located. AC means an academic site within JANET, QUB you can guess, and REDDWARF is the mail server which is our Sun workstation situated in the department. The local server may not always be shown in the internet address and to get me by email it is sufficient to use

Another sample internet address presented in 3 parts: JVSmith @ HQ.MSFC.NASA.GOV

Reading this from right to left we have GOV which means it's a U.S.Government address. NASA stands for National Aeronautics and Space Administration. MSFC stands for George C Marshall Space Flight Center in Huntsville, Alabama and HQ is obvious, Headquarters. The user's name is J V Smith.

Another interesting one is IKE@SACEUR.PENTAGON.ARMY.MIL. I'm not sure if this is a real address. How's your history? "Saceur" is Supreme Allied Commander-Europe. But who is the person with the user name IKE? Answers please to our discussion list - first there gets a mention in class.

Some of the material in these notes derived from the Roadmap course (1994) given by Patrick Douglas Crispen, The University of Alabama, University of Alabama - Tuscaloosa.

© The Queen's University of Belfast.
Patrick Brannigan
Last modified: 22 January 2006