75755.1327@compuserve.com
Normally (except on AppleLink), a domain address can only contain one @-character. When an address has to be extended with gateway routing information, replace all @-characters to the LEFT in the address by %-characters. Here is an example: BITNET uses a different addressing method (USER@SYSTEM). Let's assume that you are subscribed to the club for lovers of Japanese food (J-FOOD-L@JPNKNU10.BITNET, see chapter 6). You have a mailbox on INTERNET, and want to send a recipe to the other members using the address J-FOOD-L. On some Internet systems, you can simply use the address: J-FOOD-L@JPNKNU10.BITNET , and your mailbox system will take care of the routing for you. If this addressing method doesn't work, you can use different gateways into BITNET depending on where you live. The preferred method is to route through a gateway near to you. If living in North America, you may route CUNYVM.CUNY.EDU using the following address:
J-FOOD-L%JPNKNU10.BITNET@CUNYVM.CUNY.EDU
The rightmost @ in this address is maintained. The one to the LEFT has been replaced with a %. The term ".BITNET" tells the gateway machine where to forward the message. The following will happen: First, the message will be sent to system CUNYVM at the EDUcation site CUNY. CUNYVM investigates the address, and discovers that the message is for BITNET. It cuts off all text to the right of "JPNKNU10," and replaces the % with an @. The message is forwarded to the mailbox J-FOOD-L on the BITNET system JPNKNU10 at the Kinki University in Japan.
Bang addressing ———————- "Bang" is American for "exclamation point" (!). The UUCP network uses this variation of the domain addressing scheme. Example: User Jill Small on Econet in San Francisco used to have the address pyramid!cdp!jsmall . Read this address from right to left. The name of her mailbox is to the right. The name of the organization is in the middle. "Pyramid" is the name of the network. Some email systems can use bang addresses directly. (Note that the ! character has a special function on Unix computers. Here, you may have to type the address as pyramid\!cdp\!jsmall to avoid unwanted error messages. The \ character tells Unix to regard the next character as a character, and not as a system command. This character may also have to precede other special characters.) Other systems do not accept bang addresses directly. Here, the users must send such messages through a gateway. The American host UUNET is a frequently used gateway. If routing through UUNET, you may write the address like this:
pyramid!cdp!jsmall@uunet.uu.net
If your system absolutely refuses to accept exclamation points in addresses, try to turn the address into a typical Internet address. Write the address elements in the Internet sequence (left to right). Replace the exclamation points with %-s, like this:
jsmall%cdp%pyramid@uunet.uu.net
This method works most of the time. When it works, use this addressing form. Bang paths may fail if an intermediate site in the path happens to be down. (There is a trend for UUCP sites to register Internet domain names. This helps alleviate the problem of path failures.) Some messages must be routed through many gateways to reach their destination. This is the longest address that I have used, and it did work:
hpda!hplabs!hpscdc!hp-lsd.cos.hp.com!oldcolo!dave@uunet.uu.net