On 2021-05-17 at 08:00:30 UTC-0400 (Mon, 17 May 2021 14:00:30 +0200)
Magnus Harlander <mag...@harlan.de>
is rumored to have said:
Is this really a good idea?
Not really.
For mail which does not originate within the scope of your authority to
set policy, you would be interfering with the intent of a sender who is
not normally subject to your rules and with what they are trying to
communicate to their correspondents. This will inevitably create
conflict, because in many cases it is desirable to have all recipients
aware of who else is receiving a message (particularly a meeting
invitation) and to enable the ad hoc mailing list-like functionality
that comes from everyone in a conversation using "Reply All"
consciously.
It also will break any existing DKIM signatures and in the case of
calendar items where you are modifying the body of the message it will
also break OpenPGP and S/MIME signatures, which are typically applied by
the MUA.
Of course, ultimately the traditional maxim applies: "Your server, your
rules." No one is going to stop you from doing this with a server you
control. Since you are comfortable using Perl, you might want to
implement this on top of the existing MIMEDefang milter, which is
designed for doing radical message surgery of this sort and is
configured by implementing Perl subroutines for each of the milter
phases. That would spare you from using header_checks and body_checks
(which are very limited.)
--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire
