move read messages to mbox?

[J Moore <jaymo@xxxxxxxxxxxx>]

No doubt my confusion comes from having learned pine first, but...

when I quit mutt, I'm always asked if I want to move read messages to 
/home/jaymo/mbox(y/n). By selecting the default (no) I leave my messages 
in /var/mail/jaymo. 

I have a few files that I've created in /home/jaymo/Mail that I use to
save messages I want to retain. I think mutt defaulted to this dir.  
There currently is no '/home/jaymo/mbox' dir.

Here's my confusion: what's the relationship between '/home/jaymo/mbox' 
and '/home/jaymo/Mail'? Why did mutt select these two (different) 
directories?

Thanks,
Jay