Mail from 10.8.2 – Can this work on a Mac running 10.5.8?

I have 2 Macs but basically use my newest (MacBook Pro-13" mid-2010) running Mountain Lion 10.8.2. But this Mac has had problems (2 motherboards replaced in first 15 months - glad for the extended guarantee I purchased)-- and although doing fine now, I would like to have the ability to use my PBG4 (Feb 2005) in case of problems with the MBP.

I have daily and weekly backups of my MBP so the worse data loss would be 23 hours. If I wake-up one morning and the MBP is dead, can I take the Mail Folder from the LaCie HD backup and drop that into my PowerBook G4 and have the PBG4's version of Mail find my messages and such?

If so: Do I simply take my Mail folder from MYMACHD/users/myname/Library/Mail and put it in the same location on my PBG4?

If not: What to do?

Thanks for any guidance here.

Best regards,

Steve Schulte

Friday 8 February 2013