Severe Mail Problems after formatting and reinstalling OSX

Hi there.

Like everybody knows, PCs performance does not last long, not for Windows PCs, not even for a Mac,

since 2007 I use Macs only and kept on with my behaviour to format the Harddrive and reinstall OSX regularly,

about every 6 month. I was always proud in Mac, cause it was easy.

The things that must never be lost are Mail and Safari. I copied the Mail and Safari folder from the Library on

a USB stick and after re-intalling OSX I put them into their place and my Accounts and Emails are back, BÄÄM !!! Nice !

This worked the last 9 or so years, every time. I never lost my important mails. It always worked, all 20 or so times.

But not yesterday, I put the folder where it belongs but nothing, tried it a few times, nothing.

I use the time machine since two month and thought this might save the day. I started the time machine and let it

recover my Mail folder in the Library. It did not work !

So I thought: This is a failure, darn it, do it all again. And I formatted the Hard Drive and reinstalled OSX and I did it again.

It does not work. I always worked, 9 years it worked. But not anymore.

What can I do ?

Hope anybody can help !