sendmail, 4th Edition

userdb

Look up in the User Database V8.7 and later

The User Database is a special database file that you create for use by sendmail. It causes sender and recipient addresses to be rewritten under control of an external database. Ordinarily, any local address is first looked up in the aliases database. If it is not found there, that user’s ~/.forward is next examined. If the User Database is enabled, the address is looked up in that database after aliasing and before forwarding, but only if the selected delivery agent has the F=@ flag set (F=@ on page 766).

In the sections that follow, we describe the use of this database in detail, but first we will note a few important points.

Although we illustrate here that a lookup can be done using a database file, a remote lookup can also be done via a User Database server, or via a network service. Those forms of lookup are described in UserDatabaseSpec on page 1116.

You can also look up addresses in the User Database with rule sets using this userdb database-map type. To do so, you declare it like this:

Kname userdb  switches  field

Here, the name is the name you will use in later rule sets. The field is either a literal maildrop or mailname (see Create the User Database on page 944). The possible switches are shown in Table 23-29.

Table 23-29. The userdb database-map type K command switches

Switch	§	Description
-a	-a on page 887	Append tag on successful match.
-D	-D on page 887	Don’t use this database map if DeliveryMode=defer.
-f	-f