Duplicate me.com account folders under my "All Sent" mail folder

Hello Ross Novie1,

Let's use the steps below to boot your Mac into safe mode to see if that behavior persists from there:

1. Turn on or restart your Mac, then immediately press and hold the Shift key as your Mac starts up.

2. Release the key when you see the login window, then log in to your Mac. 

3. You might be asked to log in again. On either the first or second login window, you should see ”Safe Boot” in the upper-right corner of the window. If you can't start up in safe mode, make sure that your Mac isn't using a firmware password.

You can also find those steps in this resource: Use safe mode on your Mac - Apple Support

It can take a few extra minutes to boot into safe mode. Your screen may flash or flicker while in safe mode. Those behaviors are expected. Testing in safe mode runs a check on your disk, removes some cached files, and can help isolate conflicts with startup items. Once you've tested that behavior in safe mode, you can restart to leave safe mode.

Should that persist, do you have your email accounts set up on any other devices? If so, are they exhibiting a similar behavior?

Let us know, and we'll keep moving forward based on your results.

Hello Ross Novie1,

Thanks for the followup question. Sorry we didn't point more directly to help.

In here: Create or delete mailboxes in Mail on Mac - Apple Support

That photo shows the third one that you are under the On My Mac area, which means: "On My Mac: Mailboxes you create in On My Mac are local, meaning you can access them only on the Mac where you created them."

The second one is actually added for your email account, from Internet Accounts. Either for something else like Contacts or Calendars, you just enabled the Mail slider too.

The first one is either from iCloud (if you use it and signed in there) or is just a general quick access. No, they shouldn't be using double the space, but the third one is local, so that one might be using up more space.

But Mail is generally small, so if the reason you are asking is to make storage space, there are easier ways: Free up storage space on your Mac - Apple Support

Thanks.

Hi Ross Novie1,

You can also check to see if this is related to your Favorites settings with the Mail app. The guide here can help you check. Use favorite mailboxes in Mail on Mac - Apple Support

However, as the issue continues in safe mode reach out to Apple Support directly to report the issue and have them further assist. Get Support

Best.

Thanks for reaching out Ross Novie1,

It appears you're seeing two different inboxes for two of your accounts. "All Inboxes", aggregates all of your inboxes.

We hope this helps clarify. Additional information you may find helpful, can also be found here: Mail User Guide for macOS Sonoma

Cheers!