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7.3.1.5 `MMDF`

class `MMDF`( | path[, factory=None[, create=True]])

  A subclass of `Mailbox` for mailboxes in MMDF format. Parameter factory is a callable object that accepts a file-like message representation (which behaves as if opened in binary mode) and returns a custom representation. If factory is `None`, `MMDFMessage` is used as the default message representation. If create is `True`, the mailbox is created if it does not exist.

MMDF is a single-file mailbox format invented for the Multichannel Memorandum Distribution Facility, a mail transfer agent. Each message is in the same form as an mbox message but is bracketed before and after by lines containing four Control-A ("`\001`") characters. As with the mbox format, the beginning of each message is indicated by a line whose first five characters are "From ", but additional occurrences of "From " are not transformed to ">From " when storing messages because the extra message separator lines prevent mistaking such occurrences for the starts of subsequent messages.

Some `Mailbox` methods implemented by `MMDF` deserve special remarks:

`get_file`( | key)

  Using the file after calling `flush()` or `close()` on the `MMDF` instance may yield unpredictable results or raise an exception.

`lock`( | )

`unlock`( | )

  Three locking mechanisms are used--dot locking and, if available, the `flock()` and `lockf()` system calls.

See Also:

mmdf man page from tin
  A specification of MMDF format from the documentation of tin, a newsreader.

MMDF
  A Wikipedia article describing the Multichannel Memorandum Distribution Facility.