PMDF System Manager's Guide

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

1. The addresses in the mailing list file 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 can such things fail, they can 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 can 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 can 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 and 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, PMDF-XGS channels, PMDF-LAN Lotus Notes channels, or PMDF-MR MRIF channels) you should be sure to stop and restart the server each time a mailing list alias definition is changed in the alias file (or any of the files the alias file includes). (The PMDF RESTART (OpenVMS) or pmdf restart (UNIX and NT) utility provides 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 mailing list files is changed.
4. Each PMDF process sees the alias database existing as of when it first needed to access the database. This means that if you are using a permanently resident server (such as the multi-threaded SMTP server, PMDF-XGS channels, PMDF-LAN Lotus Notes channels, or PMDF-MR MRIF channels) you should be sure to stop and restart the server each time a mailing list alias definition's left hand side is changed in the alias database, and each time a mailing list definition's right hand side is changed if a new alias database file has been created (but not if an existing alias database file was updated "in place" using the PMDF CRDB/APPEND or pmdf crdb -append utility). 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 mailing list files is changed.
5. 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.
6. Be sure to observe the length restrictions associated with aliases when defining mailing lists, particularly as mailing list definitions can get rather long. Aliases in the alias database can contain up to 32 characters in a short database, up to 80 characters in a long database, and up to 252 characters in a huge database. In the cases 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 can lead to addresses being silently dropped from lists. Aliases in the alias file can contain up to 60 characters (referring here to the left hand side of the definition). The right hand side of an alias file definition is not specifically limited; however, each physical line is limited to 1024 characters---use the backslash line continuation character to continue a long definition over multiple physical lines. Thus note that particularly long mailing list definitions (definitions involving quite a few of the optional parameters) can, for reasons of length, need to be stored in a huge records alias database or in the alias file, rather than an alias database of shorter records.