Mail Domains

Within the sendmail environment, a domain is an administratively defined area of control with logical rather than physical boundaries.

You can configure three general types of domains:

root: top-level domain of the local domain space. For example, horses.com is the top level domain for the domain pintos.horses.com.
direct: the domain(s) a station can send mail to directly (no forwarders or relays involved).
local: the domain to which a station belongs.

The following parameters designate domains in the /usr/etc/configmail script and the /etc/sendmail.cf file:

configmail parameters: rootdomain, directdomain, and localdomain
sendmail.cf macros and classes:
- root domain: T macro
- direct domain: D class
- local domain: D macro