Many system administrators do not want to be bothered with the work needed to ensure that their system is able to reach all the networks (and therefore systems) on all networks worldwide. Instead of doing so, they would rather relay all outgoing mail to another system that is known to be indeed ``smart''.
RELAY_HOST defines the UUCP hostname of such a smart neighboring system.
RELAY_MAILER defines the mailer used to relay the messages there.
It is important to note that setting these parameters results in your outgoing mail being forwarded to this remote system, which will affect the load of their system. Be certain to get explicit agreement from the remote Postmaster before you configure your system to use another system as a general purpose relay host.
Thu Mar 7 23:22:06 EST 1996