If the file exists and is not an Rmail file,
the message is appended in inbox format.
+The default file name comes from `rmail-last-rmail-file',
+which is updated to the name you use in this command.
+
A prefix argument N says to output N consecutive messages
starting with the current one. Deleted messages are skipped and don't count."
(interactive
messages will be appended with pruned headers; otherwise, messages
will be appended with their original headers.
+The default file name comes from `rmail-last-file',
+which is updated to the name you use in this command.
+
The optional third argument NOATTRIBUTE, if non-nil, says not
to set the `filed' attribute, and not to display a message.