[Mimedefang] regex filter unwanted words

[dick hoogendijk]

Some time ago I asked about filtering unwanted words. The advice was /
is not to do it, but I still want to try.

The filter rule was something like:

if($Subject =~ m// ) {
 	return action_bounce("bad subject");
}

Question: do I put the unwanted words into this rule like this:

if($Subject =~ m/sex|microsoft|Watch/ ) {
 	return action_bounce("bad subject");
}

I'm not sure how to put in the regex. How many words can I put between
those two slashes of m// ?