Picking Method Of Winning???

IM NEW HERE AND HAD A QUESTION
MY QUESTION IS....WHEN THE SPONSOR HAS ALTERNATIVE ENTRY METHODS SUCH AS .....EMAIL......SNAILMAIL....HOW DO THEY DETERMINE HOW TO PICK FROM EMAIL ENTRANTS OR SNAILMAIL??
I ALWAYS WONDERED ABOUT THAT. WOULDNT IT BE A WASTE OF TIME FOR ME TO ENTER IF THEY PICK SNAILMAIL AND I ENTERED VIA EMAIL?
THANKS FOR READING.