Mail saved under On My Mac
I have had a several email folder with several years worth of Gmail emails stored in Mail under "On my Mac" which I could access anytime. So after I just upgraded from Ventura to Sonoma those Gmail folders are gone from Mail and attempts to retrieve them from ~Library/Mail are fruitless. So where do On My Mac files reside on my MacBook Pro? Is it possible to find them in Ventura basedbackup files from several days ago saved on TimeMachine. I have consently done TM and now wondering if its not the best solution. Appreciate any and all assistance.
FYI Gmail forum states emails older than 30 days are auto-deleted, from their servers I guess.
Mark R
MacBook Pro 13″, macOS 10.15