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Email addresses usually appear in one of two forms--using the Internet format which contains `@', an "at"-sign, or using the UUCP format which contains `!', an exclamation point, also called a "bang." The latter of the two, UUCP "bang" paths, is more restrictive, yet more clearly dictates how the mail will travel. invisible.xbm invisible.xbm
To reach Jim Morrison on the system south.america.org, one
would address the mail as `jm@south.america.org'. But if Jim's
account was on a UUCP site named brazil, then his address
would be `brazil!jm'. If it's possible (and one exists), try to
use the Internet form of an address; bang paths can fail if an
intermediate site in the path happens to be down. There is a growing
trend for UUCP sites to register Internet domain names, to help
alleviate the problem of path failures.
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Another symbol that enters the fray is `%'---it acts as an extra
"routing" method. For example, if the UUCP site dream is
connected to south.america.org, but doesn't have an Internet
domain name of its own, a user debbie on dream can be
reached by writing to the address
debbie%dream@south.america.org
The form is significant. This address says that the local system
should first send the mail to south.america.org. There the
address debbie%dream will turn into debbie@dream, which
will hopefully be a valid address. Then south.america.org will
handle getting the mail to the host dream, where it will be
delivered locally to debbie.
All of the intricacies of email addressing methods are fully covered in the book !%@:: A Directory of Electronic Mail Addressing and Networks published by O'Reilly and Associates, as part of their Nutshell Handbook series. It is a must for any active email user. Write to nuts@ora.com for ordering information. invisible.xbm
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