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Obvious Names, Generic Addresses and Preferred Email Addresses



It is now possible to use addresses of the form
in place of traditional email addresses of the form
The condition is that you have set your preferred email address in emdir to point to the userid and computer where you want to receive your mail.

Since this type of email address will not change (unless you change your name!), you are recommended to use it on your buisness card, when people ask for your email address, in your personal addressbook and in your mailing lists.

To find out more details, read on...

Generic Addresses - what are they and why are they useful?

Think of a telephone directory - it lists correlations between people's names and their telephone numbers. In much the same way a directory exists at CERN giving the correlations between people's names and the addresses of a computer mailbox where they want to receive their electronic mail. This directory is called EMDIR for Electronic Mail DIRectory.

The main purpose of this directory is to allow you to use electronic mail addresses for CERN users which are:

fairly easy to guess if you know the name of the person at CERN, and,

have a longer ``lifetime'' than a ``real'' electronic mail address that is tied to a particular computer or a group of computers.

This form of address is called ``generic address'', sometimes also ``obvious'' or ``user-friendly'' address. The ``generic address'' is meant to go on your business card and into addressbooks for electronic mail. An example for a generic address is:

Generic addresses are used in EMDIR in the same way as someone's name and address in a telephone directory. A ``generic address'' consists of two parts as all electronic mail addresses do: a username part and a domain part glued together with the character ``@''. Lower- or upper-case letters are treated identically.

The domain part is simply:

and the username part is the ``obvious name''.

Obvious names are constructed from data in the Computer Centre Data Base CCDB, where all people using one of the central computing services (and others) are registered. The basis for the construction of the obvious name is data provided by the CERN administration for the person concerned (usually corresponding exactly to what is written in the person's passport). An obvious name consists of a firstname part and a familyname part joined together by a `.' (period) character, e.g.:


However there are many people who are better known by a shorter or more familiar version of the firstname written in their passport, e.g. Mike instead of Michael, Nick instead of Nicolas, Jeff instead of Jeffrey and so on. Others may not like the transcription of a Russian or Indian firstname into a French or English version. These people can have a ``preferred first name'' registered in the CCDB by their group administrator. Thus, both




would then be valid obvious names.

The case of multipart firstnames and/or multipart familynames is a bit more difficult to handle. The automatic generation of obvious names will use a period character `.' everywhere between parts of the obvious name, so the obvious name of Mr. Juan Fernandez de las Vegas will be:

Note that only spaces between parts of the name are replaced by periods, other separators will be preserved unchanged, i.e. the obvious name for Ms. Marie-Claire Noelle-Neumann will be:


Preferred EMail Addresses

When you use the telephone directory, you are ``converting'' name information into a telephone number. Similarly computer programs can use EMDIR to convert a ``generic address'' to a real computer mailbox address.

The address of the mailbox which in our analogy corresponds to the telephone number is called PEM (Preferred EMail address) and has the form:



Unlike a telephone number that is given to you by the telephone company, you can choose your Preferred EMail address (PEM). If you move house and need a new telephone number you make a request to the phone company. If you move to a new computer for handling your mail, it is up to you to change your PEM. You can change it using the emdir command or your group administrator can change it using userreg. Unfortunately there is no easy way to check the validity of the information being entered in EMDIR.

One mistake that is happening quite often is to set the PEM to the generic address, but that creates a circular definition as if you would have your telephone number in the telephone directory replaced by a reference to your name.


or your PEM address will be ``out of order'' for at least one day. Usually the faulty PEM is detected the following day and replaced by the one before the erroneus change, but there is again a delay before this modification becomes effective and mail can be delivered.

Converting Generic Addresses into Preferred EMail Addresses

The conversion of a ``generic address'' into a ``preferred email address'' and the subsequent routing of electronic mail to this address is taking place on the MailServer. The conversion procedure starts by trying a very efficient exact match using the whole generic address as a pattern to search for. Should the exact match fail, a program will be run that tries to do its best to find an approximate match for the given obvious namegif. It is therefore much more efficient and less demanding on the resources of the MailServer to send mail to
(exact match)

than to send it to
(fuzzy match).

If you want to check before sending mail to a generic address that an obvious name is valid you should send mail to

specifying not more than one (possibly incomplete) obvious name to check for on the Subject: line of your mail and zero or more (possibly incomplete) obvious names (one per line) in the message body.

next up previous
Next: Mail Related Documentation Up: Special Chapter: Mail Issues Previous: How to Migrate your

Michel Goossens
CN Division
Tel. 3363
Wed Mar 13 07:42:40 MET 1996