WinError 1005 - 4 An existing connection was forcibly closed by the remote host error on downloading outlook emails via exchangelib

Question

I'm trying to run a python script to download emails from an Outlook inbox. However, every single time on the 100th email, the connection is terminated and I get the following error:

> Account [email protected]: Exception in _get_elements: Traceback (most recent call last):
> File "C:\Program Files\Python38\lib\site-packages\urllib3\connectionpool.py", line 665, in urlopen
> httplib_response = self._make_request(
> File "C:\Program Files\Python38\lib\site-packages\urllib3\connectionpool.py", line 421, in _make_request
> six.raise_from(e, None)
> File "<string>", line 3, in raise_from
> File "C:\Program Files\Python38\lib\site-packages\urllib3\connectionpool.py", line 416, in _make_request
> httplib_response = conn.getresponse()
> File "C:\Program Files\Python38\lib\http\client.py", line 1322, in getresponse
> response.begin()
> File "C:\Program Files\Python38\lib\http\client.py", line 303, in begin
> version, status, reason = self._read_status()
> File "C:\Program Files\Python38\lib\http\client.py", line 264, in _read_status
> line = str(self.fp.readline(_MAXLINE + 1), "iso-8859-1")
> File "C:\Program Files\Python38\lib\socket.py", line 669, in readinto
> return self._sock.recv_into(b)
> File "C:\Program Files\Python38\lib\ssl.py", line 1241, in recv_into
> return self.read(nbytes, buffer)
> File "C:\Program Files\Python38\lib\ssl.py", line 1099, in read
> return self._sslobj.read(len, buffer)
> ConnectionResetError: [WinError 10054] An existing connection was forcibly closed by the remote host
> 
> During handling of the above exception, another exception occurred:
> 
> Traceback (most recent call last):
> File "C:\Program Files\Python38\lib\site-packages\requests\adapters.py", line 439, in send
> resp = conn.urlopen(
> File "C:\Program Files\Python38\lib\site-packages\urllib3\connectionpool.py", line 719, in urlopen
> retries = retries.increment(
> File "C:\Program Files\Python38\lib\site-packages\urllib3\util\retry.py", line 400, in increment
> raise six.reraise(type(error), error, _stacktrace)
> File "C:\Program Files\Python38\lib\site-packages\urllib3\packages\six.py", line 734, in reraise
> raise value.with_traceback(tb)
> File "C:\Program Files\Python38\lib\site-packages\urllib3\connectionpool.py", line 665, in urlopen
> httplib_response = self._make_request(
> File "C:\Program Files\Python38\lib\site-packages\urllib3\connectionpool.py", line 421, in _make_request
> six.raise_from(e, None)
> File "<string>", line 3, in raise_from
> File "C:\Program Files\Python38\lib\site-packages\urllib3\connectionpool.py", line 416, in _make_request
> httplib_response = conn.getresponse()
> File "C:\Program Files\Python38\lib\http\client.py", line 1322, in getresponse
> response.begin()
> File "C:\Program Files\Python38\lib\http\client.py", line 303, in begin
> version, status, reason = self._read_status()
> File "C:\Program Files\Python38\lib\http\client.py", line 264, in _read_status
> line = str(self.fp.readline(_MAXLINE + 1), "iso-8859-1")
> File "C:\Program Files\Python38\lib\socket.py", line 669, in readinto
> return self._sock.recv_into(b)
> File "C:\Program Files\Python38\lib\ssl.py", line 1241, in recv_into
> return self.read(nbytes, buffer)
> File "C:\Program Files\Python38\lib\ssl.py", line 1099, in read
> return self._sslobj.read(len, buffer)
> urllib3.exceptions.ProtocolError: ('Connection aborted.', ConnectionResetError(10054, 'An existing connection was forcibly closed by the remote host', None, 10054, None))
> 
> During handling of the above exception, another exception occurred:
> 
> Traceback (most recent call last):
> File "C:\Program Files\Python38\lib\site-packages\exchangelib\services\common.py", line 330, in _get_elements
> yield from self._response_generator(payload=payload)
> File "C:\Program Files\Python38\lib\site-packages\exchangelib\services\common.py", line 292, in _response_generator
> response = self._get_response_xml(payload=payload)
> File "C:\Program Files\Python38\lib\site-packages\exchangelib\services\common.py", line 416, in _get_response_xml
> r = self._get_response(payload=payload, api_version=api_version)
> File "C:\Program Files\Python38\lib\site-packages\exchangelib\services\common.py", line 370, in _get_response
> r, session = post_ratelimited(
> File "C:\Program Files\Python38\lib\site-packages\exchangelib\util.py", line 917, in post_ratelimited
> protocol.retry_policy.raise_response_errors(r)  # Always raises an exception
> File "C:\Program Files\Python38\lib\site-packages\exchangelib\protocol.py", line 700, in raise_response_errors
> raise response.headers["TimeoutException"]
> File "C:\Program Files\Python38\lib\site-packages\exchangelib\util.py", line 843, in post_ratelimited
> r = session.post(
> File "C:\Program Files\Python38\lib\site-packages\requests\sessions.py", line 581, in post
> return self.request('POST', url, data=data, json=json, **kwargs)
> File "C:\Program Files\Python38\lib\site-packages\requests_oauthlib\oauth2_session.py", line 515, in request
> return super(OAuth2Session, self).request(
> File "C:\Program Files\Python38\lib\site-packages\requests\sessions.py", line 533, in request
> resp = self.send(prep, **send_kwargs)
> File "C:\Program Files\Python38\lib\site-packages\requests\sessions.py", line 646, in send
> r = adapter.send(request, **kwargs)
> File "C:\Program Files\Python38\lib\site-packages\requests\adapters.py", line 498, in send
> raise ConnectionError(err, request=request)
> requests.exceptions.ConnectionError: ('Connection aborted.', ConnectionResetError(10054, 'An existing connection was forcibly closed by the remote host', None, 10054, None))

Code block causing the error:

    for aNum, item in enumerate(unprocessed_emails.filter(subject__contains='Notification').order_by('-datetime_received')):

        emailBody = item.body
        emailBody = emailBody.split('has invited you to view:<br><a href="')
        emailSubject = item.subject
        link = ((emailBody[1]).split('" originalsrc="'))[0]
        #Opens link  which auto-downloads file
        #webbrowser.open_new(link)    
        r = requests.get(link, allow_redirects=True) 
        try:
            sleep(2)
            eMessage = f"{aNum} of {emailCount}: Processing email with subject:  {emailSubject}"
            myLogger.info(msg=eMessage)
            filename = getFilename_fromCd(r.headers.get('content-disposition')).replace(":","_")
        except Exception as e:
            exceptionContent = getFilename_fromCd(r.headers.get('content-disposition'))
            eMessage = str('Connection to Office365 Exchange API Failed\n' + 'Error Message:  ' + str(e) + '\nContent that caused exception:\n{exceptionContent}\nContinuing...')
            myLogger.critical(msg=eMessage)
            supportMessage = f""
            try:
                sendEmailToSupport(supportMessage)
            except Exception as e2:
                eMessage2 = str('Attempt to send email to support failed. Error Message:  ' + str(e))
                myLogger.critical(msg=eMessage2)
                continue
            continue
        print(filename)

        if "event" in emailSubject.lower():
            with open(os.path.join(SourcePath, filename), 'wb') as aFile:
                aFile.write(r.content)
        elif "alarm" in emailSubject.lower():
            with open(os.path.join(ASourcePath, filename), 'wb') as aFile:
                aFile.write(r.content)
        print(reportCounter)
        reportCounter += 1`

No idea what's causing the issue. The connection timeout occurs only on the 100th email being downloaded, I'm guessing that it's triggering some download limit, but I can't seem to find anything online.

Answer 1

Your example code is missing the part where you define the account and connection settings, but the general solution to have your script survive hitting connection errors is to set a retry policy. See https://ecederstrand.github.io/exchangelib/#fault-tolerance

Example:

credentials = Credentials(...)
config = Configuration(
  retry_policy=FaultTolerance(max_wait=3600), credentials=credentials
)
account = Account(primary_smtp_address='[email protected]', config=config)