Why do old messages keep showing as new in my Apple Mail program?

If you use the Mail program on macOS, or on an iPhone or iPad, you might find that messages you’ve previously sent suddenly appear as new messages at the top of your Inbox.

This is caused by an Apple feature called “Follow Up” that can show unanswered messages as “new”. As Apple describes it, “If you send a message and don’t receive a response in 3 days, the sent email automatically resurfaces to the top of your inbox to help you remember to follow up”.

If you don't want the Mail program to do this, you can turn off this feature. If you use both a Mac computer and an iPhone or iPad, you’ll need to turn it off on both of them.

Turning off Follow Up on an iPhone or iPad

The section you’re looking for, and the slider you want to tap, look like this:

Follow Up Suggestions

Turning off Follow Up on a macOS computer

The section you’re looking for, and the checkbox you want to uncheck, look like this:

Follow Up setting on macOS