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 like the Internet. In addition, newer UUCP connections frequently use domain-style names. Route-independent addresses can have this format:

user@host.domain

UUCP connections can use the following address format:

host.domain!user

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

user@domain

Route-independent addresses are read by searching for the @ sign, then reading the domain hierarchy from the right (the highest level) to the left (the most specific address to the right of the @ sign).