The netinfo(3) form of database is supplied with the NeXT, NeXTSTeP, OpenStep, Darwin, Mac OS 10.0, and Mac OS X operating systems. It is a network information service that provides file contents such as aliases and passwd, and locations such as the location of the sendmail.cf file. If you are running on a NeXT or under NeXTSTeP, this NETINFO will automatically be defined in your operating system's devtools/OS file. If you also define AUTO_NETINFO_ALIASES, NETINFO will automatically be used to resolve aliases. Otherwise, you will need to enable that use by declaring netinfo: in an alias declaration or by including netinfo in your service switch file (Section 12.1.1).

The netinfo(3) databases can also be used to declare netinfo type maps (Section 23.2.2) with the K configuration command.

If you are running a precompiled sendmail binary, you can use the -d0.1 debugging command-line switch (-d0.1) to determine if NETINFO support is included (if it appears in the list, support is included).