I don't recall getting an email myself for a freeroll where you have to put money in to play, but I recently got an email to their $500 Ceres Invitation tourneys. I asked a friend of mine who also has an account with PokerStars
and opened it up around the same time, but he didn't get this email. I placed in the money fairly easily if I recall - the number of players registered were a lot smaller too, less than 900 I think.
So if anything, be sure to carefully look over these emails since not all of them will be for those who make a deposit.