Denying localhost connects

With the great help from here on the list, I was able to get sendmail to
block connections from any host except localhost and some trusted
networks. I did it by first accepting trusts and then a denial of each
of the 255 networks in my access file. The spam from local connects has
virtually stopped with the exception the occasional message from
localhost. I have localhost and 127.0.0.1 as RELAY in my access file and
assume that is needed? We run Postfix on our gateways and it has a
helo_checks mechanism for denying connections from itself with an error
such as 'Your not me'. Can this be done in sendmail?

--
Robert