PMDF System Manager's Guide

There are some important restrictions that should be observed when using aliases:

1. The addresses in the alias file or database should be formatted as pure RFC 822 addresses, e.g., user@host. Do not try to use DECnet or other routing conventions that you can get away with in the rewrite rules table. Not only may such things fail, they may not produce a visible error (see the next item). Source routes are the only exotica that are permitted.
2. Certain types of bogus addresses in a list alias will not generate a "bad address" return message. Specifically, if, for a given address in the list, the system name is illegal or there is a syntax error in the address specification, then the copy of the message to that address may be silently dropped and no one will be the wiser. If the mailing list file associated with an alias does not exist, then mail to the list itself may be dropped. However, errors in the mailbox part of the address (e.g., "no such user") will be handled correctly. System managers should take care to test each list they set up to insure that all the recipient addresses are correct. The PMDF TEST/REWRITE/CHECK_EXPANSIONS (OpenVMS) or pmdf test -rewrite -check_expansions (UNIX or NT) utility provide a way to do this. Lists should be checked periodically and also whenever extensive changes are made.
3. PMDF reads the alias file only as each program using PMDF initializes itself. This means that if you are using a permanently resident server (such as the multi-threaded SMTP server or PMDF-LAN Lotus Notes channels) you should be sure to stop and restart the server each time the alias file or any of the files it includes is changed. (The PMDF RESTART (OpenVMS) or pmdf restart (UNIX and NT) utility provide a simple way to restart any such PMDF detached processes.) On the other hand, mailing list files referenced by the alias file are read and reread as needed, so servers need not be restarted when one of these files is changed.
4. The alias file is always read into memory in its entirety each time PMDF is used. All files included by the primary alias file are also loaded into memory. (Mailing list files are not loaded into memory.) The use of a huge alias file can eat up lots of memory. Liberal use of the mailing list reference operator, <, to reference long lists is recommended. Long lists of addresses coded directly into the alias file or any files it includes should be avoided. Use of an alias database for large numbers of aliases is also recommended.
5. Be sure to observe the length restrictions associated with aliases. Aliases in the alias file can contain up to 60 characters. Aliases in the database can contain up to 32 characters in a short database, up to 80 characters in a long database, and up to 252 charactes in a huge database. In the alias file, the addresses to which aliases translate can contain up to 252 characters. In the case of a short database, the translation value can contain up to 80 characters; in the case of a long database the translation value can contain up to 256 characters; in the case of a huge database the translation value can contain up to 1024 characters. In some cases failing to observe length restrictions may lead to addresses being silently dropped from lists.