My Mail crashes immediately. This is the code 0 Dispatch queue: com.apple.main-thread

I'm sorry, I don't have a solution. Usually when things like this happen it is because there is a conflict with some other app. I would ask - have you changed or added anything just prior to this occurring? Do you have an antivirus app or a Mac cleaner app installed? They are completely unnecessary and often cause problems. I would start by restarting the computer in the Safe Mode. Hold down the Shift key at restart. Be patient as this operation can take up to 10 minutes while the OS is cleaning and fixing things. Then see if the problem still exists. If not, then restart normally and retest. If so, then repost that information. There are other things that can be suggested

For what it's worth, I see complaints about the Mail app see every week. I personally gave up on it years ago and have successfully used the free Thunderbird ever since with no problems.

Well, here is the next step. I recommend that you download, install and run the free app EtreCheck. When you do, be sure to enable full disk access. It will provide a comprehensive report of your computer's operations. Then you can post that report below under "Additional text". Oftentimes those reports point us to possible issues or to known conflicts.