On Sat, Apr 13, 2019 at 06:15:33PM +0200, Rainer Dorsch via Exim-users wrote: > I want to upgrade my server from Debian Jessie to Debian Stretch. I am afraid
> that at some time during the upgrade process, there is an invalid exim
> configuration and messages get rejected. In order to avoid that I was thinking
> of either redirecting via DNS to a server which does not listen to port 25 to
> enforce the sender to try again. Or redirect via DNS to a server which buffers
> all incoming messages until the Stretch setup is tested (not sure which server
> software does this though...).
>
> Can anybody recommend one of the approaches or even propose something
> better...?
Upgrade Exim on a minimal test system and check/tune its config.
Do it before the production server upgrade.
You can also check whether old config works fine with new Exim version,
if so, keep it for future use. In Debian completely assembled config is
in file /var/lib/exim4/config.autogenerated.
--
Eugene Berdnikov
