This allows *from_* to be successfully set to a non-default value when calling mbox.get_string.

This hides unwanted implementation details from tracebacks.

robust at shutdown. If needs to release multiple resources, they are released
even if errors are occured.

in the mailbox module.  This is partial rollback of changeset f340cb045bf9.

requires them.  Disable executable bits and shebang lines in test and
benchmark files in order to prevent using a random system python, and in
source files of modules which don't provide command line interface.  Fixed
shebang line to use python3 executable in the unittestgui script.

This avoids race conditions when other programs are monitoring
the maildir directory.  Patch by janzert.

ModuleNotFoundError.

modernize some modules' code by replacing OSError->ENOENT/ENOTDIR/EPERM/EEXIST occurrences with the corresponding pep-3151 exceptions (FileNotFoundError, NotADirectoryError, etc.)

When adding a message from a binary file, \r\n was translated to
\r\r\n in the message body.

If messages were only added, a new file is no longer created and
renamed over the old file when flush() is called on an mbox, MMDF or
Babyl mailbox.

If messages were only added, a new file is no longer created and
renamed over the old file when flush() is called on an mbox, MMDF or
Babyl mailbox.

Previously mailbox was copying a list of attributes from one message object to
another in order to "copy the message data".  This means that any time new
attributes were added to email.message.Message, mailbox broke.  Now instead it
copies all attributes from the source object to the target object, skipping
any mailbox-object-specific attributes to produce the same clean initial
state it was previously getting by copying only the "known" attributes.

David Lam assisted in the development of this patch.

Closes #13254.

Closes #13254.

encoding, to read and write MH mailboxes (.mh_sequences files).

This makes them work like the close provided by regular file objects.

All of the other methods in mailbox that create message objects take care to
close the file descriptors they use, so it seems to make sense to have
__getitem__ do so as well.

Patch by Filip Gruszczyński.