Autoexpunge and special user namespace

I'm interested in replacing my cron script that expunges old deleted mail with the new feature announced in 2.2.20

• Added mailbox { autoexpunge=<time> } setting. See http://wiki2.dovecot.org/MailboxSettings for details.

To use it, I need to specify which mailbox needs them using the namespace configuration. For example

namespace inbox {
	mailbox Trash {
		auto = no
		special_use = \Trash
		autoexpunge = 7d
		mailbox_list_index = yes
	}
	mailbox trash {
		auto = no
		special_use = \Trash
		autoexpunge = 7d
		mailbox_list_index = yes
	}
	mailbox "Deleted Messages" {
		auto = no
		special_use = \Trash
		autoexpunge = 7d
		mailbox_list_index = yes
	}
	mailbox "Deleted Items" {
		auto = no
		special_use = \Trash
		autoexpunge = 7d
		mailbox_list_index = yes
	}
	...
}

Different readers use different mailboxes, so I include the common ones. Some questions:

1) Do I need the special_user configuration at all?  Will some
clients start using different mailboxes to store deleted mail
if I keep the special_use lines?

2) I also expunge old mail in INBOX marked as deleted -- is
there any way to handle this case?  Create virtual mailbox?

Joseph Tam jtam.home@gmail.com