Re: [Fetchmail-users] IDLE Socket error After IP reconnect

[Matthias A. <mat...@gm...>]

Am 01.11.25 um 11:44 schrieb LolliPOPsystem--- via Fetchmail-users:
> Hi,
>
> New User here.
>
> Setup: Running a Python script starting one instance for each of multiple mail accounts in IDLE mode leveraging individual $FETCHMAILHOME environment variables like this:
> https://www.linuxquestions.org/questions/linux-software-2/correct-fetchmail-with-idle-and-multiple-servers-config-642089/
>
> Fetchmail runs behind a router with Dynamic IP.
>
> Occationally (and particularly After IP resets), I receive the following error for each instance and the script restarts the fetchmail instances:
>
> Nov 01 08:48:54 fetchmail: Received BYE response from IMAP server:  TIMEOUT

This would be a server employing short timeouts... you can work around 
that with idletimeout 280 or similar (in rcfile or command line 
argument) on supported versions of fetchmail. Check after what time the 
server gives you a TIMEOUT and then set idletimeout several seconds 
short of that.

> Nov 01 08:48:54 fetchmail: re-poll failed
> Nov 01 08:48:54 fetchmail: socket error while fetching from…
>
> I assume this is due to the IP change and the connection cannot be re-established. I think this will Not harm fetchmail’s functionality and I can safely restart it without fearing any mail will be lost or not fetched.

Yes, assuming the server is compliant and does _not_ try to be extra 
smart and delete the message after the first attempt to read it.

Worst case if the IP changes in the middle of a transfer you might end 
up with two copies of a message, one complete and one incomplete.

> Can you confirm this understanding and maybe explain better what is Happening and what an elegant way is to mitigate?

The elegant ways are 1. don't use IDLE if the server employs 
nonconforming timeouts, 2. get a static IP.

The practical way is "ignore and move on".