PMDF System Manager's Guide
PMDF-REF-6.0

To forward mail for a few selected users, use the alias file. If, however, you will be doing this for several thousand users, then use the alias database. The difference between the two is that the alias file is loaded into memory while the alias database, intended for large numbers of aliases, is not. The alias database is a keyed, indexed file and has excellent performance even when it contains over a hundred thousand aliases.
On OpenVMS systems, the database is an RMS keyed, indexed file, and may be tuned with RMS tuning tools, if necessary.

Suppose you wish to forward mail for the two local users Judy.Public and jdoe to, respectively, pjudy@vaxa.acme.com and johndoe%a1@mr.xyzzy.org. To do this with the alias file you would simply add to the PMDF alias file, the two entries

Judy.Public:       pjudy@vaxa.acme.com 
jdoe:              johndoe%a1@mr.xyzzy.org 

To add these two entries to your alias database you should locate the source file used to generate that database, add these two entries to that file, and then regenerate the database with the PMDF CRDB (OpenVMS) or pmdf crdb (UNIX and NT) utility. There is no need to recompile your configuration after making changes to the alias database. However, resident servers (such as the PMDF SMTP server) may need to be restarted if you wish them to see the change immediately.

On OpenVMS or UNIX systems, you may instead add these entries to the alias database using the PMDF DB (OpenVMS) or pmdf db (UNIX) utility. See the appropriate edition of the PMDF User's Guide for more details.

There are several points that you should note:

• PMDF's aliases only affect mail passing through PMDF. For instance, in the above example, the jdoe alias will have no effect for mail sent with VMS MAIL to JDOE unless you also forward JDOE's mail to IN%JDOE:

  $ MAIL
  MAIL> SET FORWARD/USER=JDOE IN%JDOE
  MAIL> EXIT
  $ 
  

  This forwarding causes mail sent to JDOE to be handled by PMDF. This then allows PMDF's alias for jdoe to then take effect.
• Aliases are case insensitive. The alias for Judy.Public will match judy.public, JUDY.PUBLIC, JuDy.PUBlic, etc.
• Aliases only apply to local addresses, or to addresses matching a channel marked with the aliaslocal channel keyword. They do not apply to arbitrary addresses, such as in messages passing through your system for a different host (unless that host is handled by a PMDF channel marked aliaslocal).
• Aliases only affect the envelope To: address. The message header will not be rewritten; i.e., the alias will not be expanded into the message header.
• In a similar vein to the previous item, messages passing through your system with an address such as johndoe%a1@xyzzy.org will not have that address magically replaced with the alias jdoe@local-host. The ability to do this is, however, very useful and may be accomplished with the address reversal database or REVERSE mapping. If you wish to do this, then refer to Section 3.6 .