Hi, I'm Ashik. Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP
Press Command, Option and Esc keys. This will bring Force Quit window. Select Mail and click Force Quit. Open Mail. Does it work now ?
If that didn't work, then turn your Mac off. Turn it back on and immediately hold down Command, Option, P and R keys at the same time for 5seconds, then release the keys and immediately hold down Shift key for 20 seconds. This will boot into Safe Mode. Does Mail work in Safe Mode ?
Please let me know if that didn't work, so we can continue troubleshooting.
Please follow the steps below to fix the problem.
Hi there, How is it going ?