Below is what contents of the file should contain:

# Begining of file
#
# LDAP Schema for Intranet Mail Routing
# Reference: draft-lachman-laser-ldap-mail-routing-02
# 
# This file has been tested using OpenLDAP (www.openldap.org).
# Save this file as mail-routing.oc.conf and add a line to your slapd.conf:
# include    /usr/local/etc/openldap/mail-routing.oc.conf
#
# Add an additional inattribute mailLocalAddress        cis
attribute mailRoutingAddress      cis
attribute mailHost                cis
objectClass inetLocalMailRecipient
   requires
      objectClass
   allows
      mailLocalAddress,
      mailRoutingAddress,
      mailHost
# End of File






This would deliver mail for tom@example.com to thomas@mailhost.example.com.

        dn: uid=dick, o=example.com, c=US
        objectClass: inetLocalMailRecipient
        mailLocalAddress: dick@example.com
        mailHost: eng.example.com







[admin@linux named]$ cat supan.com.hosts | grep MX
uio.supan.com.		IN	MX	5	uio.supan.com.
uio.supan.com.		IN	MX	10	supan.com.
@		IN	MX	5	supan.com.