On Thu, Aug 01 2013, Lars Magne Ingebrigtsen wrote:
> David Edmondson <dme@dme.org> writes:
>
>> Currently \Deleted messages appear as read. I'm fine with them appearing
>> as read, but would like something more as well (expired seems ideal, but
>> anything that I can use to avoid them showing up in groups where
>> "(display . all)" is the norm).
>
> The "E" mark is for expirable articles, not expired articles, so that
> doesn't seem ideal.
>
> I think "marked as read" is the best we can do.

This annoyed me again, so I looked more. `nnimap-update-info' is not
easy to follow!

This change gets me to where I want to be:

diff --git a/lisp/nnimap.el b/lisp/nnimap.el
index 016a8a2..8661fff 100644
--- a/lisp/nnimap.el
+++ b/lisp/nnimap.el
@@ -154,7 +154,7 @@ textual parts.")
   '((read "\\Seen" %Seen)
     (tick "\\Flagged" %Flagged)
     (reply "\\Answered" %Answered)
-    (expire "gnus-expire")
+    (expire "gnus-expire" %Deleted)
     (dormant "gnus-dormant")
     (score "gnus-score")
     (save "gnus-save")

Summary: deleted articles are give the "expire" mark. From there I can
do what I like on that basis.

Conveniently, it's a data-only change, so it's easy for me to make in my
.gnus.el.