resetting Mail on Sonoma

I am having issues with mail. My mail server is on rackspace and every time I try to get mail or send mail the application quits. I also have a gmail account and an icloud account and they work fine. To get mail to restart, after the program quits, I have to go in and turn the accounts off in settings and then open mail. I have tried deleting the accounts and recreating them numerous times. As a test, I created a new user on my mac and mail works perfectly well there. Sadly, my HD does not have enough space on it to copy all my files and then like under a new user name. Can anyone tell me howe to delete the data in mail and get a new factory reset on it?