Apple Mail Crashing

Hello,

I have an iMac here that Apple Mail keeps crashing and I have tried all these things:

- Disk first aid

- Safe mode

- Onyx to rebuild Apple Mail Indexes. That did not work at first.

- Safe Mode - Mail will open fine

- When I go back to Normal Mode - Mail will not open and a crash report comes back up.

- Normal Mode - Disconnected or Connected to the internet - Mail does not open.

This iMac has not been connected to the internet for 6-12 months. It was being kept as an as-is archive.

The iMac has 3 Exchange email accounts and 1 iCloud email account and hundreds of thousands of emails which range from 2020 and dating back to the 90's.

- I did try running Onyx again. I selected to Delete the Existing Mailbox Index and Spotlight as well. Then I ran it again to Rebuild The Index.

- After this I could open Apple Mail and was "Importing Messages”. However when that is done, the crash report comes back up and Apple Mail will not open. I have done this twice with the same result.

I have now run the EtreCheck app and have attached the report.

Any assistance you can provide would be greatly appreciated!