PMDF System Manager's Guide

Before implementing a centralized naming scheme you must first determine what address format you want to use. First.Last@domain is becoming more and more popular although there remains the issue of what to do when you have two users named Mike Smith. ^c

Without a doubt, RFC 822 is the most heavily used addressing format in the world today. When choosing a format, make sure that it does not rub RFC 822 the wrong way: even if your organization does not use RFC 822 based messaging, much of the world does. A lot of people outside your organization may want or need to exchange mail with your users. Similarly, your users might find it desirable to have addresses which are easily gatewayed to or through the Internet. If this is not the case, then the likelihood that their addresses will be altered to the point of being unreplyable is increased. Watch out for characters called "specials" in RFC 822 as they will require quoting if they appear in the mailbox part of an address. The RFC 822 specials are

SPACE ( ) < > @ , ; : \ " . [ ]

Use of any special (other than period, which is handled differently --- periods are usually safe as long as they do not appear adjacent to one another or at the very beginning or very end of an address) is disasterous as many misconfigured or otherwise broken mailers do not properly handle addresses with quoting. Underscores, although not a special, can also lead to problems. Many gateways convert spaces to underscores and underscores to something else (hopefully). Often the address is not properly inverted when coming back out the gateway or when it is transported elsewhere. Some messaging formats such as X.400 do not even allow underscores in addresses. As of this writing a heavily used AT&T gateway removes the first underscore and everything following it in the mailbox part of addresses presented to it.