def parse_kwargs(kwargs):
    """
    Extract variables from kwargs.

    :param server: SMTP email server.
    :type server: str

    :param port: Port to use.
    :type port: int

    :param username: Email address.
    :type username: str

    :param password: Email password, optional.
    :type password: str
    """
    server = kwargs['server']
    username = kwargs['username']
    port = kwargs['port']
    password = kwargs['password']
    return server, username, port, password
