maybe you could tell me why my script stops

[komarek]

i have this script on raspbian
and  sometimes it fails and stops
could you help me to understand what's the problem?

here is the log of the script:

Error:
 
Traceback (most recent call last):
  File "Documents/PY/cancelloaperto.py", line 46, in <module>
    client.loop_forever()
  File "/usr/local/lib/python3.4/dist-packages/paho/mqtt/client.py", line 1378, in loop_forever
    rc = self.loop(timeout, max_packets)
  File "/usr/local/lib/python3.4/dist-packages/paho/mqtt/client.py", line 897, in loop
    rc = self.loop_read(max_packets)
  File "/usr/local/lib/python3.4/dist-packages/paho/mqtt/client.py", line 1177, in loop_read
    rc = self._packet_read()
  File "/usr/local/lib/python3.4/dist-packages/paho/mqtt/client.py", line 1766, in _packet_read
    rc = self._packet_handle()
  File "/usr/local/lib/python3.4/dist-packages/paho/mqtt/client.py", line 2239, in _packet_handle
    return self._handle_publish()
  File "/usr/local/lib/python3.4/dist-packages/paho/mqtt/client.py", line 2414, in _handle_publish
    self._handle_on_message(message)
  File "/usr/local/lib/python3.4/dist-packages/paho/mqtt/client.py", line 2574, in _handle_on_message
    self.on_message(self, self._userdata, message)
  File "Documents/PY/cancelloaperto.py", line 37, in on_message
    inviamail("Cancello Aperto", "[email protected]", "Appena aperto il cancello\nalle ore " + tempo)
  File "Documents/PY/cancelloaperto.py", line 17, in inviamail
    server = smtplib.SMTP('smtp.gmail.com:587')
  File "/usr/lib/python3.4/smtplib.py", line 242, in __init__
    (code, msg) = self.connect(host, port)
  File "/usr/lib/python3.4/smtplib.py", line 321, in connect
    self.sock = self._get_socket(host, port, self.timeout)
  File "/usr/lib/python3.4/smtplib.py", line 292, in _get_socket
    self.source_address)
  File "/usr/lib/python3.4/socket.py", line 491, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
  File "/usr/lib/python3.4/socket.py", line 530, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -2] Name or service not known

here's my code (i changed email details)

#!/usr/bin/env python3
import os
import paho.mqtt.publish as publish
import paho.mqtt.client as mqtt
import time
import smtplib
import requests
from datetime import datetime

def inviamail(sogg, dest, testo):
        fromaddr = '[email protected]'
        toaddrs  = dest
        msg = testo
        sub = sogg
        username = '[email protected]'
        password = 'xxxxxx'
        server = smtplib.SMTP('smtp.gmail.com:587')
        server.ehlo()
        server.starttls()
        server.login(username,password)
        message = 'Subject: {}\n\n{}'.format(sub, msg)
        server.sendmail(fromaddr, toaddrs, message)
        server.quit()
        return

while True:
        def on_connect(client, userdata, flags, rc):
                #print("Connected with result code "+str(rc))
                client.subscribe("mytopic")

        def on_message(client, userdata, msg):
                messaggio = str(msg.payload)
                if "APERTO" in messaggio:
                        t = datetime.now().time()
                        tempo = str(t)[0:8]
                        print(tempo+" - ACCESSO")
                        inviamail("Cancello Aperto", "[email protected]", "Appena aperto il cancello\$
                        client.disconnect()

        client = mqtt.Client()
        client.on_connect = on_connect
        client.on_message = on_message

        client.connect("127.0.0.1",1883,60)

        client.loop_forever()