I have never used Groupon, Restaurant.com, or Travelzoo. Yes I am old fashioned, don't even have a smart phone, LOL. I have several questions for anybody that has used these. 1. After payment, do they just send you a voucher in the mail, or can you get them via e-mail? 2. How far in advance of your trip should order them? 3. Has any restaurant ever denied use of any coupon/voucher? 4. Do you like them? Thank you all.