Because Sun's DNS routines are supported only when you are running NIS, and because the Eagle installation disables NIS on your system, several steps are necessary to configure the sendmail program. (These steps do not apply to AIX and HP-UX systems; just to Sun's.) Before doing so, obtain from your Internet service provider the hostname of its main mail-relay machine. The example below uses relay.net.provider so be sure to use your provider's true mail-relay hostname instead.