Email flag colour isn’t changed.

Not all email providers support different colored flags. If your provider doesn’t, the flags default to red. iCloud and other Apple mail servers (.mac,, .me, etc) support colored flags. As do MS Exchange accounts.

Hi IanMaxLee,

Thank you for posting in Apple Support Communities! From our understanding, when you change the color of your flagged message, it changes back to the default red flag after switching to a different app, is that right? Is this happening on the latest version of iOS 15 ( 15.2)?

Has your iPhone been restarted since noticing this issue? You can close out the Mail app completely and then restart your iPhone.

Check out the following resources:

Close an app on your iPhone or iPod touch

Restart your iPhone

Hope that helps!