regular expressions

Good morning. I am starting in the PMG world, and I want to create mail blocking rules by regular expressions in the body of the mail, I have done it through the mail subject but I can't find a way for the body, any idea? Is it possible to do it? Thanks in advance for your help.

Good afternoon! After we started specifying domains in the blacklist through regular expressions Oct 11 11:37:08 mx3.domain.com pmg-smtp-filter[312196]: WARNING: ^* matches null string many times in regex; marked by <-- HERE in m/^* <-- HERE .cle.co$/ at /usr/share/perl5/PMG/RuleDB/WhoRegex.pm...