Gnus expiry-target and maildir

[sven . bretfeld]

Hello to all

I'm a complete newbie to Gnus, but I could solve most of my starting
problems by reading appropriate documentations. There is one thing left
I cannot solve alone.

I'm trying to tell Gnus to save expired mail in a
maildir-directory. This is what I have in my .gnus.el:

(setq gnus-directory "~/.Mail")
(setq message-directory "~/.Mail/Mail")
(setq message-auto-save-directory "~/.Mail/drafts")

(setq
 gnus-select-method '(nnmaildir "Mail" (directory "~/.Mail/"))
 mail-sources '((maildir :path "~/.Mail/" :subdirs ("cur" "new")))
 mail-source-delete-incoming t)
 (setq gnus-secondary-select-methods nil)
 (setq gnus-message-archive-group "nnmaildir+Mail:outbox")
 (setq gnus-summary-same-subject "")
 (setq gnus-sum-thread-tree-root "")
 (setq gnus-sum-thread-tree-single-indent "")
 (setq gnus-sum-thread-tree-leaf-with-other "+-> ")
 (setq gnus-sum-thread-tree-vertical "|")
 (setq gnus-sum-thread-tree-single-leaf "`-> ")
 (setq message-generate-headers-first t)
 (setq nnmail-expiry-target "nnmaildir+Mail:expired")

The last line should make expired mail to be stored in a maildir
~/.Mail/expired/. At least I think so from reading the manuals. However,
if I mark an email as expirable ("E") and run gnus-group-expire-articles
(or just leave the summary buffer) it just vanishes, seemingly deleted
from the disk. The folder ~/.Mail/expired/ stays empty. (I try it with
old spam-mail, so it's not a loss. Of course, I make read mail visible
when entering the group, that's not the mistake.) 

But what can be the problem?

Thanks for suggestions

Sven