First of all: Thanks that you are a contributing member
Regarding your question:
Yep it's possible using /etc/mail/access, just add an entry of the form:
firstname.lastname@example.org 550 Rejected due massive amout of spam!
domain.com 550 Rejected due massive amout of spam!
Check /usr/share/doc/sendmail-8.11.6/README.cf, section access_db for more information regarding this!