[Dovecot] Mailbox creation with Spam

[Master Abi]

Hi all,

I got dovecot working, but I would like to know when and what creates 
the mailbox (cur, new, trash, etc ). I noticed that when a client 
connects for the first time that mailbox is created or when a mail 
arrives for the first time (i think).

I would like to give each mailbox a Spam folder, and possibly doing this 
automatically. Is this possible with some dovecot setting and not via 
scripting.

Thanks

master