Unless I'm mistaken, isn't it kind of on a rotating basis if you're active on the site and every once in awhile you get a PM requesting or inviting you to vote?
"The voters for each contest are chosen among the people who have entered one of the last 4 contests and received at least 5 votes total in those contests. If you are chosen as a voter, you will get a special PM that will link to the voting page. "
What is the 'authorised voting list' ??
Thanks :)