I had sent actual invitations, and each invitation had a flyer inside that clearly read the deposit book by date, then also had RSVP cards with a date close to the TA book by date. I went through the same thing you did, how to tactfully say ummmm are you coming or what?!? Call them and chat, and coy fully mention the wedding, thats what I did. Or you could send another email, and make it look like a mass email, and say thanks to all the ppl that booked, here's the resort info, whatever, and if you haven't booked yet here is the TA s number... Sorry I can't be more helpful!