So, I was looking for an 'old' [pre-09] email in my Mail program and for some reason [now forgotten = I might have done an archive, for all I know/remember] I couldn't find any in my now-running program. No problemo.
I opened Time Machine. This program is an included part of Apple's Mac OSX Leopard operating system. Not a separate purchase at all. Found the 12/29/08 and 01/05/09 folders and restored both [made sure that I chose to restore both, not overwrite, and once done put the date on the folder, so they now say "Mail 12/29/08" etc. My 'original' current Mail folder is just fine and operating as it should be AND now I have a pre-newyears and post newyears copy of Mail and I can just burn the folders to a DVD and stop stewing....
Great program and just runs, doesn't force you to remember to run it.
And yes, I also use SuperDuper to make clones and full backups, but TM works great for what one needs, restoring a certain thing one finds one needs....Hurrah!!!
THE RULE: Besides death and taxes, one reality of life is your computer/harddrive/data will fail. Having reliable backups and a backup strategy is required!