Maildir subdirectories

Dear List,

As the documentation for mailbox.Maildir notes:

>>>>>>
Maildir mailboxes contain three subdirectories, namely: tmp, new, and
cur. Messages are created momentarily in the tmp subdirectory and then
moved to the new subdirectory to finalize delivery. A mail user agent
may subsequently move the message to the cur subdirectory and store
information about the state of the message in a special =93info=94 section
appended to its file name.
<<<<<<

Unless I am reading the source wrongly, however, the library doesn't
actually provide a way to do this.  MaildirMessage.set_subdir()
affects new messages, but doesn't seem to be a way to actually move a
message from 'new' to 'cur'.

What is the approved way to do this?

Best wishes,

Nicholas