Adding Late Comers to a Sequence of Daily emails so that they get the already sent emails and catchup with those who were in the sequence ontime?

Ok here is what happened. Each year we do a challenge that people sign up for and for 6 days they receive an email a day with things to do. At the end of the challenge we have select winners. Typically we only allow people to join the challenge by a certain date. So the email sequence has a start date and then wait a day timers for each email.

This year we are allowing people to sign up after the challenge has started…so we need to send them the emails that have already previously gone out and have them wait at the current timer with all the rest of the challenge members. So if I join on day 3 of the challenge I will receive Day 1, 2 & 3 emails and now I am waiting for day 4 with everyone else.

Has anyone done some like that/ What is the best way to handle that?