A reminder will automatically send a nudge email to all reviewers in the workflow (including the approver) who have not pushed their green button either on the proof’s due date, 1 hour, 3 hours, 1 day, 2 days, or 3 days before the proof’s deadline.
To set a reminder:
On the proof’s set up screen (or the proof’s info pane after the proof has been created), click the reminder icon and choose one (or multiple) of the following options:
On due date
1 hour
3 hours
1 day
2 days
3 days

Tip: You can also set a default reminder under your profile settings.