Often it is necessary to send all outgoing mail via the relay host from the corporate network. This is not so difficult to specify that for Solaris’ sendmail.
Find this row in sendmail.mc and specify your relay host name or IP instead of relay.sun.com in my example:
cp sendmail.cf /etc/mail/sendmail.cf
svcadm restart svc:/network/smtp:sendmail
that’s all. To test you can use mailx:
echo "This is the body."| mailx -s "Test subject" firstname.lastname@example.org