def perUserExpiration():
        """
        Indicate whether the message expiration policy differs per user.

        @rtype: L{bool}
        @return: C{True} when the message expiration policy differs per user,
            C{False} otherwise.
        """

        Indicate whether the message expiration policy differs per user.

        @rtype: L{bool}
        @return: C{True} when the message expiration policy differs per user,
            C{False} otherwise.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/interfaces.py