Where does mail store data(mail boxes/messages)?

PatrickJT wrote:

I have a MacBook Pro with Catalina 10.15.7. ( hard disk wiped & Catalina reinstalled a week ago). then Time machine backup did not have any Mail folders.

Now Time machine still does not backup Mail.

Furthermore I can't find stored mail data on my hard drive -I have looked in Users/Patrick/Library/Mail/V3 but there are no folders - although shutting down & rebooting & opening Mail DOES have the latest mails.

Help I'm at a loss!

Typically you can find your Mail folders from the Finder>Go>Go to Folder copy &paste:

~/Library/Mail/

Hi PatrickJT,

We understand your Time Machine is not working properly. We're happy to offer some guidance.

If Time Machine is unable to backup a certain item or you're seeing an error, you can try these basic steps: Time Machine troubleshooting on Mac

If you're still unable to back up certain items with Time Machine, we'd recommend contacting Apple for assistance: Get Support

Hope this helps. Cheers!