When using the ph delivery agent, actual delivery is through the phquery(8) program, which looks up user information in the CCSO nameserver database, then injects that mail back into sendmail for delivery.^[7] This program cannot be used by itself because you must also install the qi server, and include your own database of user information.

^[7] V8.10 introduced the ph database map (ph), which allows sendmail to perform direct ph queries, and thereby avoid this double processing.

Support is included in your mc configuration file like this:

MAILER(`local')      define first
MAILER(`phquery')    define second

Note that the local delivery agent must be defined before you can define phquery.

The defaults for the ph delivery agent are shown in Table 20-10, along with the mc configuration macros used to alter those defaults.

The phquery and qi programs are available from http://www-dev.cso.uiuc.edu/ph/.