for a multi[le select list to pass multiple values, the name must end with "[]"
change:
<select name="Course" size="4" multiple id="Course">
to:
<select name="Course[]" size="4" multiple id="Course">
I do not see any problem with the suffix select list that would cause the suffix to be missing from the email, but I do see issues with other elements on the page.
Form Element name may contain only Letters and Numbers. the only exception to that rule is the Underscore character.
you have elements on your page that have names containing spaces and punctuation:
<select name="Referral Source?" id="Referral_Source?" tabindex="150">
these are not valid element names.