[Other] Check all mail accounts fails with error "[Errno -3] Temporary failure in name resolution"

[duko1234]

Hi,

I have installed paperless-ng in a docker on a synology NAS. So far everything works fine, except pulling documents from e-mail.
The regular "check all mail accounts" task fails with the following error message:

[Errno -3] Temporary failure in name resolution : Traceback (most recent call last):
File "/usr/local/lib/python3.8/dist-packages/django_q/cluster.py", line 432, in worker
res = f(*task["args"], **task["kwargs"])
File "/app/paperless/src/paperless_mail/tasks.py", line 14, in process_mail_accounts
total_new_documents += MailAccountHandler().handle_mail_account(
File "/app/paperless/src/paperless_mail/mail.py", line 157, in handle_mail_account
with get_mailbox(account.imap_server,
File "/app/paperless/src/paperless_mail/mail.py", line 97, in get_mailbox
mailbox = MailBox(server, port)
File "/usr/local/lib/python3.8/dist-packages/imap_tools/mailbox.py", line 290, in __init__
super().__init__()
File "/usr/local/lib/python3.8/dist-packages/imap_tools/mailbox.py", line 32, in __init__
self.box = self._get_mailbox_client()
File "/usr/local/lib/python3.8/dist-packages/imap_tools/mailbox.py", line 305, in _get_mailbox_client
return imaplib.IMAP4_SSL(self._host, self._port, self._keyfile, self._certfile, self._ssl_context)
File "/usr/lib/python3.8/imaplib.py", line 1297, in __init__
IMAP4.__init__(self, host, port)
File "/usr/lib/python3.8/imaplib.py", line 198, in __init__
self.open(host, port)
File "/usr/lib/python3.8/imaplib.py", line 1310, in open
IMAP4.open(self, host, port)
File "/usr/lib/python3.8/imaplib.py", line 303, in open
self.sock = self._create_socket()
File "/usr/lib/python3.8/imaplib.py", line 1300, in _create_socket
sock = IMAP4._create_socket(self)
File "/usr/lib/python3.8/imaplib.py", line 293, in _create_socket
return socket.create_connection((host, self.port))
File "/usr/lib/python3.8/socket.py", line 787, in create_connection
for res in getaddrinfo(host, port, 0, SOCK_STREAM):
File "/usr/lib/python3.8/socket.py", line 918, in getaddrinfo
for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -3] Temporary failure in name resolution

I also have a pi-hole running in a docker on the same NAS.

Does anybody have any suggestions how to solve that problem?

Thanks in advance!

Andreas

[cryptoluks]

• Try to do name resolution from within the container.

docker ps -a
docker exec -it <container name/id> sh

• Are you using Pi-Hole as DHCP server? And does your NAS has a static or dynamic DHCP address? If DHCP of Pi-Hole is used, Pi-Holes DNS are pushed to the client.
• Check /etc/resolv.conf on host and container.
• Try to hardcode DNS servers in /etc/resolv.conf of host and container temporarily.

[duko1234]

Hi,

thanks for the reply!

Are you using Pi-Hole as DHCP server? And does your NAS has a static or dynamic DHCP address? If DHCP of Pi-Hole is used, Pi-Holes DNS are pushed to the client.

• PiHole is not my DHCP server, the router is.
• The NAS has a dynamic DHCP address.
• I also get the correct DNS server from the DHCP server.

Check /etc/resolv.conf on host and container.
Try to hardcode DNS servers in /etc/resolv.conf of host and container temporarily.

• The IP of the PiHole was automatically configured in the resolv.conf files both on the host and in the container.

Once I set the DNS on the synology to 8.8.8.8, paperless could access the mail server.
There seems to be a problem with accessing a local DNS server in another docker container.

The pi-hole has network mode host, paperless has bridge mode. I will try to change bridge mode to host mode for paperless as well in order to get it to run with my local DNS.

[henfri]

Did you set the port of your Mailserver in paperless?

[duko1234]

Did you set the port of your Mailserver in paperless?

I set imap.gmail.com and 993 for the mailserver.