Hmmm... Not sure this is an email address! Could you enter it again, please?
Hmmm... This doesn't look like a postal code. Mind entering it again?
It doesn't look like that postal code exists anywhere.
Don't worry, we only use your postal code to show you your riding, and we don't share it with anyone.
or
We use your postal code to determine which riding or municipality you're in.
or
We use your riding to show you candidates and policies relevant to you.