Apple Mail custom flag names revert to color names after restart

This looks like a bug, not a feature. Custom flag names are meant to persist across restarts. When Mail falls back to “Green,” “Blue,” etc., it usually means it isn’t saving its preferences properly.

Some background that helps explain it: the flag color is stored on the mail server with each message, which is why your flagged messages stay flagged. Apple Mail encodes the color as a combination of special IMAP keywords ($MailFlagBit0, $MailFlagBit1 and $MailFlagBit2). The flag names, however, are only a local display setting on your Mac. If that local setting doesn’t get written or read correctly, Mail falls back to the default color names.

Here are a few things to try, in order:

1. 
   
2. Quit Mail properly. Rename a flag, then quit Mail with Mail > Quit Mail (⌘Q), not Force Quit, and reopen it. If the Mac shuts down or Mail is force-quit, changed preferences may not get saved.
3. 
   
4. 
   
5. Restart in Safe Mode, then restart normally. This clears some system caches. Open Mail, rename the flags again, and quit and reopen to test.
6. 
   
7. 
   
8. Check iCloud syncing of Mail settings. In System Settings > [your name] > iCloud, look at whether Mail is set to sync. Settings syncing from another Mac or device can sometimes overwrite local changes. Try toggling it off, renaming the flags, and restarting Mail.
9. 
   
10. 
    
11. Test in a different user account. Create a temporary user account, add one email account, name a flag, and restart Mail. If the name sticks there, the problem is in your user’s Mail preferences. If it doesn’t, it’s likely a bug in this macOS version.
12. 
    
13. 
    
14. Report it to Apple. If nothing works, send feedback at apple.com/feedback/mail.html or through the Feedback Assistant app, so Apple knows the issue affects this release. A future update may fix it.
15. 
    

Hope this helps!

Apple Mail custom flag names revert to colour names after restart

Is this a bug or a feature?

This appears to be a bug rather than intended behaviour. Apple Mail supports custom flag names, so a flag named “Vacations” should retain that name after quitting and reopening Mail.

Since flagged messages remain flagged and their colours are unchanged, the issue appears limited to the flag names. However, without further testing or confirmation from Apple, the precise cause cannot be established.

I could not confirm whether Apple has acknowledged this specific issue in Mail 16 on macOS 27.0.1 (Golden Gate).

How to troubleshoot the problem

1. Rename a flag and test it

1. Open Mail and expand the Flagged section in the sidebar.
2. Double-click the flag name, change it to “Vacations,” and press Return.
3. Quit Mail completely using Mail >> Quit Mail (or Command-Q).
4. Reopen Mail and check whether the name persists.

For Apple's general Mail instructions, see the Mail User Guide.

If the name reverts to “Green,” proceed to the next step.

2. Check for macOS updates

Open System Settings >> General >> Software Update and check for a newer compatible macOS release.

Apple's macOS User Guide provides general guidance on managing macOS settings.

I could not verify that a specific macOS update fixes this flag-naming issue.

3. Contact Apple Support

If the problem persists, contact Apple Support or submit feedback through  the  Product Feedback - and make it known to Apple regarding this ongoing issue

Provide the following information:

• MacBook Pro (M1, 2020).
• macOS 27.0.1 (Golden Gate).
• Apple Mail 16.
• Custom flag names revert to their default colour names after quitting and reopening Mail.
• Flagged messages remain flagged, and their colors do not change.

Include the full macOS build number, if available, and mention when the problem first appeared.

I would avoid deleting Mail preference files, rebuilding mailboxes, or changing iCloud settings without evidence that these actions are relevant to the problem.

One useful detail to include in the report: Did the problem begin immediately after upgrading to macOS 27, or had the custom flag names been working correctly for some time before they began reverting?

Thanks for the suggestions. I quit Mail after renaming the labels, and they were fine when I started Mail again. I also restarted my computer and the names persisted. I have no idea why it seemed to work.

We'll see what happens in the future.

I have exactly the same problem.

Even tried to reset all mail accounts, but it didn’t help.

I cannot say wether it began after the update to macOS 27, because I have migrated from Outlook to Apple Mail after the update and did not use Apple Mail before.

• MacBook Pro M4 Pro, macOS 27.0.1 (26A434), Mail 16.0 (3901.100.1.1.12)

Same problem here, Golden Gate 27.2 now, rename, quit and restart Mail: flags back to colour names. The 27.2 update did not solve this...

Well, after restarting in Safe Mode the flags all went back to their color names. Hmm...

I give up. We've been Apple users since Lisa, and I'm more frustrated with the company and its products nearly every day. I'll report the problem, but, frankly, I doubt they'll have a solution and my guess is their response will be to upgrade my hardware.