(while (re-search-backward "^X-Gnus-Newsgroup: " beg t)
(delete-region (point) (progn (forward-line 1) (point)))))
(when nnmail-cache-accepted-message-ids
(while (re-search-backward "^X-Gnus-Newsgroup: " beg t)
(delete-region (point) (progn (forward-line 1) (point)))))
(when nnmail-cache-accepted-message-ids