Auto Newsletter Question

We are tying to figure out a way to send registered users an email that would inform them that there is a new posting on the website at the end of the day. However, there will be times that we have many updates to the website during a single day and we would like to avoid sending users a large number of emails. Ideally, we would like to be able to send one email saying something like “New post(s) uploaded for Exmissions. Please visit website to view the updated post(s).” Is there a way to auto send something like that only once if a post is created in a particular category?