Can Captain create autoresponse emails that include sequential numbers

We are about to have a free event which is likely to draw hundreds more people than our permitted occupancy. We don’t want people be disappointed when they can’t get in.

What we want people to do is sign up online and receive an auto response that includes a sequential “ticket” number that they can present at the door. We would like to limit the number of these numbered responses to the occupancy number.

We want to use numbers so that (1) the tickets are easily transferable, (2) we can more quickly tick them off as they arrive, and (3) keep track of numbers that do not arrive by a certain time so that we can let standby’s into those empty spots.

The form itself would be very simple–just name and email address.

We are an all volunteer non-profit organization and we need to keep the administration of this event really simple while staying in the good graces of the Fire Marshall. Any advice you can give will be much appreciated.