Q: mail quit unexpectedly

Hi. Try the steps suggested here: If Mail unexpectedly quits when viewing certain messages - Apple Support

Open the Go menu with the Option key pressed - Open Library - Containers and move the folder ‘com.apple.mail’ to the desktop.

Restart your Mac and check whether everything works fine.

Take a look at this Apple Support article and follow the troubleshooting steps you can find there:

Mail (Yosemite): Mail troubleshooting

Try Safe Boot:

- Shut down your Mac

- Wait until your computer turns off and after that press the Power button

- Right after you hear the startup tone, press and hold the Shift key

- Release the Shift key when you see a grey Apple sign and the progress bar below this sign

- After your Mac boots up, restart it as you usually do.

Did the suggestion below work for you?

If mail app is corrupted to resolve the issue : Click go > hold option key & don't release it > library > Macintosh HD  > users > user name > library > containers > com.apple.mail > Data > library > preferences > right click on com.apple.mail.plist & move to trash .

Restart from apple logo & empty the trash .

This was a splendid solution. It worked perfectly. My thanks to you, "appreciate"

Best Regards,

Patrick

you are welcome , we put efforts to sort out the issues .