Maybe my point wasn't stated clear enough: the crontab itself is in spool, obviously, but the scripts started from crontab entries reside in my home directory. And while a procmailrc can live in some spool too, the files to be delivered into are in my home directory too.
So then you have two choices: Move them elsewhere, and be able to encrypt the rest of $HOME, or don't encrypt $HOME. This gives you additional options for protecting your home directory if you want it. Noone is forcing you.
