What might suddenly provoke this poplib error?

[MRAB]

On 2022-10-13 13:47, Chris Green wrote:
> I have a short python3 program that collects E-Mails from a 'catchall'
> mailbox, sends the few that might be interesting to me and dumps the
> rest.
> 
> It has suddenly (after working for some years) started throwing the
> following:-
> 
>      Traceback (most recent call last):
>        File "/home/chris/.mutt/bin/getCatchall.py", line 83, in <module>
>          pop3.pass_('brzmilla')
>        File "/usr/lib/python3.10/poplib.py", line 218, in pass_
>          return self._shortcmd('PASS %s' % pswd)
>        File "/usr/lib/python3.10/poplib.py", line 181, in _shortcmd
>          return self._getresp()
>        File "/usr/lib/python3.10/poplib.py", line 157, in _getresp
>          raise error_proto(resp)
>      poplib.error_proto: b'-ERR internal server error'
> 
> 
> The section of code throwing the error is as follows:-
> 
>      #
>      #
>      # Connect to the POP3 server, get message count, exit if no messages
>      #
>      for t in range(10):         # retry 10 times
>          try:
>              pop3 = poplib.POP3_SSL('mail3.gridhost.co.uk',timeout=300)
>              break
>          except TimeoutError:
>              if t == 9:
>                  log.err("Timed out 10 times, giving up")
>                  exit(1)
>              else:
>                  log.warn("Timed out, try " + str(t))
> 
>      pop3.user('catchall at isbd.net')
>      pop3.pass_('brzmilla')
>      numMessages = len(pop3.list()[1])
>      if (numMessages == 0):
>          break
> 
> 
> It seems to be saying that the POP3 server has a problem, if so there's not
> much I can do about it as it's my hosting provider's mail server.  Is it
> really saying the server has a problem?
> 
As you've already ascertained that it's a server error, I'd just like to 
suggest that you add a sleep before retrying. If it has timed out after 
5 minutes, I doubt there's much point in retrying immediately.