Submit email only if check box is ticked

Submit email only if check box is ticked

I have a form with two decision boxes:

-Send Case ID to Cust?
-Send escalation notification to cust?

At present I have a Send Mail on input for each
of these decision boxes; Problem is an email is
sent everytime you tick or untick the box.

What is the syntax necessited to have the email sent
ONLY on VALIDATE, IF boxes are checked?