def starttls(self, tls):
        reply = self.custom_command(b'STARTTLS')
        if reply.code == '220':
            self.encrypt(tls)
        return reply
Sends the STARTTLS command with identifier string and waits for the
dataset/ETHPy150Open slimta/python-slimta/slimta/smtp/client.py/Client.starttls