How to remove blue box around emails

Hi there Kim,

Based on the details you provided so far, we're not quite sure what is is you're asking to remove from within the Mail app in your Mac. That being said, we'd be happy to help however we can.

Where is this 'blue box' showing within Mail, and when did it first appear? The more details you provide, the better equipped we'll be to assist.

We see from your post you have macOS 12.1, but the latest version is macOS 12.2. You can verify this by clicking on the Apple logo at the top left corner of the screen, then on ‘About This Mac’. Here's how to first Back up your Mac with Time Machine, and afterwards, here's How to update the software on your Mac.

Cheers!

If you are talking about the blue box that appears when you click on an email received, you can open mail and go to mail>preferences>viewing...scroll down to where it talks about highlight messages and pick a color