Complete backup with Nandroid

How to backup everything with Nandroid?

Actually I am asking as I did a backup recently but while restoring some of my apps went missing (like email), why did that happen?

I am not too familiar with /preload but what I have read have made me understand that it includes some of the apps so might this be the case that the apps in /preload weren't backed up? If yes how to include them to back up with android, please tell (I did some search but didn't found any answer).

Any advice/help would be really appreciated.

Thanks