Verify if the Milter protocol is supported. If not, follow the procedures To verify if you have Milter support enabled. These steps add the necessary lines to the build configuration file in the Sendmail directory and build a new version of Sendmail.
To verify if you have Milter support enabled
To compile Sendmail 8.12 to use external mail filters
sh Build -c
/usr/lib/sendmail -bt -d0 < /dev/null