do the following:

Write email, save it, send it.  Do it again.  Second time gives error:
`Selecting deleted buffer'.

Expectation would be no error, because overriding expiry-target in
drafts group parameters.

Debugger entered--Lisp error: (error "Selecting deleted buffer")
  nnml-add-nov("archive" 6 [nil "test 4" "Gnus Test <gnustest@thysbe.localdomain>" "Sat, 25 Sep 2010 21:26:11 -0500" "<81sk0x9r5m.fsf@totally-fudged-out-message-id>" nil 0 0 "thysbe.fqdn.ackermath.info archive:6" ((To . "nils"))])
  nnml-save-mail((("archive" . 6)) "" t)
  nnml-request-accept-article("archive" "" nil)
  gnus-request-accept-article("nnml:archive" nil nil t)
  nnmail-expiry-target-group("nnml:archive" "drafts")
  nnmh-request-expire-articles((4) "drafts" nil t)
  apply(nnmh-request-expire-articles ((4) "drafts" nil t))
  nnoo-parent-function(nndraft nnmh-request-expire-articles ((4) "drafts" nil t))
  nndraft-request-expire-articles((4) "drafts" nil t)
  message-disassociate-draft()
  message-send(nil)
  message-send-and-exit(nil)
  call-interactively(message-send-and-exit nil nil)


The upshot is: setting an nnml archive group as expiry target globally
and (expiry-target . delete) for the draft group (which is the default)
does not work for saved drafts.  After sending a saved article from the
drafts group gnus attempts to expire twice instead of simply deleting
the article.

Cheers,
Nils