Hello tamingdoom,
Thanks for using Apple Support Communities. It sounds like you’re having issues with Mail. I’m happy to provide some steps that may help. If you haven’t already, I suggest restarting your Mac and making sure you’re running the latest software:
How to update the software on your Mac - Apple Support
Should the issue persist, I suggest starting in safe mode and testing in a different user account:
Use safe mode to isolate issues with your Mac - Apple Support
How to test an issue in another user account on your Mac - Apple Support
Should the issue not persist in safe mode, the new user, or both, I’d advise deleting the account and then re-adding it. Keep in mind that if you use a POP email account, your emails will not be available on your Mac. I suggest creating a backup before doing this step if that’s the case:
Back up your Mac with Time Machine - Apple Support
You can find instructions for removing the account, as well as re-adding it below:
Add or remove email accounts in Mail on Mac - Apple Support
Take care.