'Retrieve a file containing the contents of a message.
@type i: L{int}
@param i: The 0-based index of a message.
@rtype: file-like object
@return: A file containing the message.
@raise ValueError or IndexError: When the index does not correspond to
a message in the mailbox.  The use of ValueError is preferred.'

def getMessage(self, i):

    raise ValueError
