eM Client version 6 was not available on the Mac, so that won’t work.
If you have eM Client version 6 installed on a PC, install the latest version of eM Client for Windows on that computer. You will automatically be prompted to import your old data. If not use Menu > File > Import > eM Client 6.
Once that is done, use Menu > Backup. This will create a zip file which you can copy to the Mac and restore using Menu > File > Restore.
The folders i am missing have been stored on my local drive. I can see the.dat files in the backup zip files of which I have many. They are stored in a separate directory in my documents folder. My backup disk crashed so cant do a recover. Every time I try to do a restore from a backup, it tells me the backup is incompatible with my current version. I am running it on a Mac, not Windows. I have so many important emails in those folders. My contacts are missing too. Anyadvice,thanks.
One thing you can try is to manually extract the zip file to a new folder on your computer.
Then in eM Client, go to Menu > Settings > General > Storage, first make a note of the current database location, and then select the new folder where you extracted the zip file as your database directory.