async def write_message_data(self, data: bytes, timeout: NumType = None) -> None:
        """
        Encode and write email message data.

        Automatically quotes lines beginning with a period per RFC821.
        Lone \\\\r and \\\\n characters are converted to \\\\r\\\\n
        characters.
        """
        data = LINE_ENDINGS_REGEX.sub(b"\r\n", data)
        data = PERIOD_REGEX.sub(b"..", data)
        if not data.endswith(b"\r\n"):
            data += b"\r\n"
        data += b".\r\n"

        await self.write_and_drain(data, timeout=timeout)
Encode and write email message data.

        Automatically quotes lines beginning with a period per RFC821.
        Lone \\\\r and \\\\n characters are converted to \\\\r\\\\n
        characters.