How to blacklist/whitelist email id and domain in sendmail using spamassassin

Edit file local.cf 

# vim /etc/mail/spamassassin/local.cf        

###wirte below paramet and bla

blacklist_from *@example.com

blacklist_from xyz@gmail.com
blacklist_from *.example.com

whitelist_from  *@xyz.com
whitelist_from abc@gmail.com

Restart spamassassin service

#/etc/init.d/spamassassin restart