There are a decent amount of guests we invited to the wedding that have not responded whether they will be attending or not. How proper do/should I be while contacting them regarding their attendance? I'm especially wondering the best way to go about asking someone about their attendance that has told others they will not be attending. I'm not sure if their response got lost in the mail or they just decided to not send it. The due date for the responses is past due FYI - we waited almost a week to see what would come late.