One of the most popular email services, Gmail keeps track of all your emails with threaded conversations, tags, and Google-powered search to find any message you need.
Email each page proof with the decision question and due time.
Your reviewer gets the proof and a clear deadline by email. You choose the question they need to answer.
Deliver the current proof for your review with a decision deadline.
Your reviewer gets the current proof and a clear decision deadline by email when a card is ready for review.
Send the maker the reviewed proof and corrections to make next.
Your maker gets a rework email that names the reviewed proof and fixes due next.