Mail Crashes

Greetings, ojsebi.

It appears that the Mail application on your Mac mini isn't working as expected. It opens several instances of the Mail app, then it quits. I'm happy to help.

macOS Sierra: Quit apps -- Make certain the Mail app is completely closed, then restart the Mail app while holding down the shift key. If the Mail application opens as it should, quit the Mail application and start it normally.

How to turn on or turn off your Mac -- If the issue persists, restart your Mac then test the issue.

Use safe mode to isolate issues with your Mac -- Test how it responds in safe mode. If there are no issues, reboot normally and test again in your own user account. Remember this when booting in safe mode: Limited graphics performance in OS X recovery or safe mode

How to test an issue in another user account on your Mac -- If the issue is also happening in safe mode, use this article to create and test another user account. This will demonstrate if the issue is isolated to your account, or if it's system wide.

Let me know how that goes.

Take care!

Thank you getting back to us with that information, ojsebi. It's appreciated. I do have some following questions for you to answer, please?

1. When you started your Mac in safe mode, how did it respond?
2. Did the issue appear in a new user account?

Let me know when you're able and have an excellent day!