I do not think they send out any rejection letter until 30 spots are taken, they will send offer in every 2 weeks and depending on how many people decline the offer in the previous round, they will give it to some more, I assume for now they have already send out 30 offers and if there are some decline, people lower in the list will get a chance. It is sad they do it this way but I think they will need to be sure they are not oversubcribed or undersubcribed. If everyone accept the offers in previous round, we can forget about it