Hello, please see https://lists.exim.org/lurker/message/20130307.235129.7eabc9f1.en.html where Phil Pennock explains what he thinks about what happens inside of Exim.
I don't know if you could and want to change Exim's behaviour for Debian. Thanks & greetings, Paul -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org