+** You can set `gnus-mark-copied-or-moved-articles-as-expirable' to a
+non-`nil' value so that articles that have been read may be marked as
+expirable automatically when copying or moving them to a group that has
+auto-expire turned on. The default is `nil' and copying and moving of
+articles behave as before; i.e., the expirable marks will be unchanged
+except that the marks will be removed when copying or moving articles to
+a group that has not turned auto-expire on. *Note Expiring Mail::.
+