HELP - Lost Mail Folders - Any way to recover?

Question

All of my custom email folders have disappeared. This is tragic, as my last backup was several months ago (yes yes... I know this is my own fault). After reading around online here, I see that the Preferences file can get corrupted if hard drive space is low. I am guessing that this is my problem, since I had Photoshop running at the same time, and only 6gig free on my 80gig drive, and remember a pop-up window appearing in Photoshop saying that my hard drive space was low.
This being the case -- just because a preference file gets deleted/messed-up, does this mean that there is NO way to recover those messages? What happened to those original files of mine that held those messages? I must have had 30 folders, and all of them are zapped from my hard drive? Not in the trash, not in the POP folders in my Library, not anywhere when I do a Find for their name. I just don't understand how they could disappear completely, and isn't there a chance that there is some recoverable data somewhere on my drive??
I also don't understand why my Junk Mail, Sent Mail and InBox mail was NOT deleted. Only the folders that I had created to file my messages. And I didn't have to re-setup my accounts or do anything like that.
Thanks in advance for any advice that anybody might be able to share.
G4 Titanium Powerbook   Mac OS X (10.4.4)   Mail 2.0.5

Answer 1

Hi all. I sure appreciate everybody's suggestions and feedback. Even though ultimately things have not worked out for me, I have a renewed faith in the Apple community as a whole -- which counts for something.
I'll try to sum up what happened for me. First, my mail folders/mbox files were nowhere to be found on my computer (either by looking in that specific heirarchy or by doing a Find for their names). Also, I did not delete any accounts at the time of the problem. I DID delete a folder from within Mail that showed up at the top of my Mail list, named "/" and which contained a single folder named "library" (I think?) which contained a single folder named "mail" or something to that effect. Basically, several folders nested within each other, with the bottom folder being caled "INBOX" (written like that) and containing mail that I had not seen before. I selected all, dragged it to my real InBox, and then deleted the top-level folder from Mail's list (named "/"). It was shortly thereafter that I lost all of my mail folders. I've never seen a mailbox folder just add itself to the list like that -- has anybody else? And then combine that with the fact that I was running a huge Photoshop file and had maxed out my hard drive's empty space as PS used it up for memory... So basically it evidently all set up a situation that caused corruption on a huge level, and caused me to lose every custom mailbox that I had defined, but not my InBox, Drafts, Sent Mail or Junk. (Luckily my Junk mail was saved, eh? How lucky for me. ha ha)
With the advice of folks here and at the Apple store and on the phone with data-saving software reps, I tried Disk Utility to first repair permissions and then fix the disk. It did find a few things on both tests, and I did repair them -- but Mail still wouldn't pull up those folders. I also ran TechTool and Data Rescue II on my drive (TAKING HOURS AND HOURS) -- but no luck.
Nobody ever seemed to think I would have much luck, but I had to give it a shot, since losing all of that mail was going to be hard for me.
And so this afternoon, I have come to the conclusion that my situation is hopeless, and I need to get back the use of my Powerbook (I have huge deadlines that I'm really behind on now, because of all of this down-time having software check my drive).
The lesson here, boys and girls, is to not take lightly the significance of hard drive space -- and to not only backup your most important files (like I did)... but to also back up your mail folder regularly... as well as any other quirky little things that might not seem obvious, but which if were eliminated from your life, would make you sad.
So thanks again to all who posted their suggestions -- it was worth my effort to give everything a shot, even though unfortunately there was not a happy ending.