CheckForSuspiciousSender

Hi there;
Rt-3.6.1 apache2, modperl2,mysql5

How does the sub CheckForSuspiciousSender in lib/RT/Interface/Email.pm work .
I though if it returned 1, it should stop the message from being submitted to the database?? I have quite few postmaster and mailer-deamon tickets/updates and I want to put stop to this??

Regards;
Roy