In addition to the new gTLDs, up to 28 new registrars will be established to grant registrations for second-level domain names. To guide future registrar developments, under Swiss law a Council of Registrars (CORE) association will be established to create and enforce requirements for registrar operations. The full text of the IAHC report is available at http://www.iahc.org.

Table 1-4 shows the top-level domains for the United States and European countries. The book !%@:: A Directory of Electronic Mail Addressing and Networks, written by Donnalyn Frey and Rick Adams, contains a complete list of domain addresses and is updated periodically. See the bibliography for a complete reference.

The following are examples of education, commercial, and government domain addresses:

roy@shibumi.cc.columbia.edu
rose@haggis.ssctr.bcm.tmc.edu
smallberries%mill.uucp@physics.uchicago.edu
day@concave.convex.com
paul@basic.ppg.com
angel@enterprise.arc.nasa.gov

This is a French domain address:

hobbit@ilog.ilog.fr

And this is a British address:

fred@uk.ac.aberdeen.kc

Note that some British and New Zealand networks write their mail addresses from top-level to lower level, but most gateways automatically translate the address into the commonly used order (that is, lower level to higher).

Mail Addressing

The mail address contains the name of the recipient and the system where the mail message is delivered. When you are administering a small mail system that does not use a naming service, addressing mail is easy: Login names uniquely identify users.

Mail addressing becomes more complex, however, when you are administering a mail system that has more than one system with mailboxes or one or more domains. It also becomes more complex when you have a uucp (or other) mail connection to the outside world. Mail addresses can be route-based, route-independent, or a mixture of the two.

Route-Based Addressing

Route-based addressing requires the sender of an email message to specify not only the local address (typically a username) and its final destination but also the route that the message must take to reach its final destination. Route-based addresses, which are fairly common on uucp networks, have this format:

host!path!user

Whenever you see an exclamation point (bang) as part of an email address, all (or some) of the route was specified by the sender. Route-based addresses are always read from left to right. For example, an email address that looks like

castle!sun!sierra!hplabs!ucbvax!winsor

is sent to user winsor on the system named ucbvax by going first from castle to the address sun, then to sierra, then to hplabs, and finally to ucbvax. (Note that this is an example and not an actual route.) If any of the four mail handlers is out of commission, the message will be delayed or returned as undeliverable.

Route-Independent Addressing

Route-independent addressing requires the sender of an email message to specify the name of the recipient and the final destination address. Route-independent addresses usually indicate the use of a high-speed network, such as the Internet. In addition, newer uucp connections frequently use domain-style names. Route-independent addresses have this format:

user@host.domain

The increased popularity of the domain hierarchical naming scheme for computers across the country is making route-independent addresses more common. In fact, the most common route-independent address omits the host name from the address and relies on the domain-naming service to properly identify the final destination of the email message:

user@domain

Route-independent addresses are read by searching for the @ sign and then reading the domain hierarchy from the right (the highest level) to the left (the most specific address to the right of the @ sign). For example, an email address such as winsor@Eng.sun.com is resolved starting with the .com commercial domain, then the sun company name domain, and finally the Eng department domain.