The opposite condition also occurs. Frequently, systems may have a number of direct UUCP connections that are used infrequently or that are not as reliable and always available as the default mailer or relay host.
For example, in the Seattle area there are a number of systems that exchange the various distributions via anonymous UUCP when the distributions are released. These systems talk UUCP only when necessary, so it is generally faster and more reliable to send mail through multiple very reliable hops and common (and always available) relay hosts.
It is easily possible to prevent UUCP delivery of mail to a host that you are directly connected to. If the remote system has a fully-qualified domain name, you can add an entry like this to the domaintable:
This will replace any occurence of the UUCP name with the FQDN, and thus prevent a match by the UUCPNODES line in the sendmail.m4 file. The result is generally that mail will go via the RELAY_MAILER and RELAY_HOST (or DEFAULT_MAILER).