[Exim] help

Hi List.

I am still trying to come to grips with regex's.

I am using the one below to reject variations on "SEX"

\b[Ss][ ./_*-]*[Ee][ ./_*-]*[Xx]\b

Is this syntax correct.
I have tested using various mails and so far no false positives.
Have tried S e X, SeX, S-E-X, which matched AND Sussex,essex & asexual,
which did not match.

Just need some "expert" advise.

thanks

Regards,
Tom