Mail quit unexpectedly on Mac

1. Quit the Mail app, then reopening it while holding the Shift key on the left-hand side of your keyboard.
   
2. Restart your Mac by clicking the Apple  menu and selecting "Restart..." from the drop down.
   
3. Test to see if the Mail app quits in safe mode. You can get information on safe mode, including how to boot to it, in this article: Try safe mode if your Mac doesn‘t finish starting up
   
   Even though the title of the article isn't the same issue as what you're experiencing, safe mode is still a great step to try--it will run a scan of your system during boot, and will then disable certain software and processes that could be causing a conflict with your Mail app. Open the Mail app in safe mode, and see if it quits. Make not of the results, then restart the computer and try opening the Mail app again.
   
4. Test the Mail app in a new user account. The following article provides information on why testing in another user account can be helpful, as well as walks you through how to set up a new account: How to test an issue in another user account on your Mac
   

Do a backup, preferably 2 on 2 separate drives.

Quit Mail.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J. When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder. Go to Library/Containers/com.apple.mail. Move the folder com.apple.mail to your desktop. You must move the entire folder, not just the contents.

Restart, re-launch Mail and test. If the problem is solved, recreate any required Mail settings and import any emails you want to save from the folder on the desktop. You can then put the folder in the Trash. If the problem remains, return the folder to where you got it replacing the one that is there.

If that doesn’t solve it repeat the above using Containers/com.apple.MailServiceAgent.

Information learned from Linc Davis. Thanks to leonie for some information contained in this.

Mail crashing

Crashes/quits unexpectedly

Hello !

Please click on go to go library and type ~/Library see internet Plug-ins , input methods , Launch agents folder are empty .

Also clear contents ( you can use command + A to select , command + Delete to delete ) of folder caches , cookies , saved application state into the trash .

Restart and empty the trash .

Please follow the article : macOS Sierra: If an app freezes or quits unexpectedly

I hope so it might be help out .

Thanks !

Thank you! You got mine going again with the shift key. You're the best. 🙂