Subject: I don't think it's a bug

From: Stephane Ascoet <[email-masked]>
Date: Wed, 16 Oct 2019 10:30:21 +0200

I think that you need to configure Exim for relaying mails to the 
outside. You can see 
<https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=688098> for a 
possible deeper way to solve the issue, sadly nobody seems to care for 
bugs in Exim4-config(like in so many other too)