There are about 8 emails that I cannot delete from my Mail. These messages do not show in my Outlook account, only on the app and I have tried multiple times to delete. The error message is same: The specified object was not found in the store., The process failed to get the correct properties.
MacBook Pro 14″
Rebuilding the affected Mailbox often resolves that particular problem. If all else fails remove the affected email account(s), and add them again.
Instructions:
Rebuild mailboxes in Mail on Mac - Apple Support
You can rebuild just the affected Mailbox, or all Mailboxes. Rebuilding all of them will take longer than rebuilding just one.
Remove or temporarily turn off email accounts in Mail on Mac - Apple Support
It doesn't generally help to just "turn off" the affected email account. Remove it first, and then add it again:
Add email accounts in Mail on Mac - Apple Support
Adding a Microsoft Exchange email account will initiate Microsoft's sign in / credential verification process, which will vary according to the way those accounts are configured.
Cannot delete emails using mail app on MacBook Pro
