Remove contractors from all internal email groups such as $All Staff, IR35 purposes

[SueEllen]

I nearly always get staff emails but the body of the email states that contractors (and random other categories of workers) are excluded.

<Rant>One of the annoying things is when they are targeting female technical workers they send you the email about 20 times as they really can't believe that they really don't have that many female technical staff.</Rant>