Q9806 - Exim/exim GitHub Wiki
How do I get exim not to add a Sender: header to locally originated mail?
It adds it only if the From: header doesn't correspond to the user
sending the message. You can suppress this by setting
no_local_from_check
. If your real question is How do I submit mail
from UUCP without it adding Sender:?, see `FAQ/UUCP/Q1503`_.