I have a friend who has used this flavor of UNIX before.
He said to try these files as well:
/etc/mail/mailsurr. There is a man page, mailsurr.
/etc/mail/mailcnfg. Look at the man page as well, mailcnfg.
Also, look at these files as well.
/etc/mail/namefiles points to /etc/mail/names.
Read this man page for help also, mailalias.