Your Mac has a nifty feature called Stickies which are basically digital sticky notes. And, for those who have used or still use physical sticky notes, you know how handy they can be. You can jot down a reminder, an idea, or a to-do so that you don’t forget it.
Having these Stickies on your Mac lets you accomplish the same thing. So, for emails in the Mail app that you need to follow up on, want to read later, or just want to keep close at hand, turn them into sticky notes.