Mail Monitor -- Spam filter - Only one header of several is processed

Centaur, I do not think it applies in this case, as only part of the text needs to match.

In classic regexp-matching software (meaning Perl) the relation "matches" is defined on pairs (string, regexp) so that S matches R if S contains a substring that exactly matches R. If one wants to test for an exact match but not substring match, one adds the beginning anchor ^ on the left and the end anchor $ on the right.