Make nnimap support IMAP namespaces

* lisp/gnus/nnimap.el (nnimap-use-namespaces): Introduce new
server variable.
(nnimap-group-to-imap, nnimap-get-groups): Transform IMAP group
names to Gnus group name by stripping / prefixing personal
namespace prefix.
(nnimap-open-connection-1): Ask server for namespaces and store
them.

* lisp/gnus/nnimap.el (nnimap-request-group-scan)
(nnimap-request-create-group, nnimap-request-delete-group)
(nnimap-request-rename-group, nnimap-request-move-article)
(nnimap-process-expiry-targets)
(nnimap-request-update-group-status)
(nnimap-request-accept-article, nnimap-request-list)
(nnimap-retrieve-group-data-early, nnimap-change-group)
(nnimap-split-incoming-mail): Use nnimap-group-to-imap.
(nnimap-group-to-imap): New function to map Gnus group names to
IMAP folder names.  (Bug#21057)

1 files changed, 6 insertions, 0 deletions

diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index 6793ed2e9f1..6ccb9e55f31 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -14320,6 +14320,12 @@ fetch all textual parts, while leaving the rest on the server.
 If non-@code{nil}, record all @acronym{IMAP} commands in the
 @samp{"*imap log*"} buffer.
 
+@item nnimap-use-namespaces
+If non-@code{nil}, omit the IMAP namespace prefix in nnimap group
+names.  If your IMAP mailboxes are called something like @samp{INBOX}
+and @samp{INBOX.Lists.emacs}, but you'd like the nnimap group names to
+be @samp{INBOX} and @samp{Lists.emacs}, you should enable this option.
+
 @end table