In reference to:
http://lists.debian.org/debian-project/2008/12/msg00151.html
8<----------------------------------------------------------------------------------
If you sign up for mail from mailing lists, just discard mail that you
don't want to read that comes in from us with Priority: bulk or List-*
headers instead of bouncing it. A mailing list is little more than a
glorified mail forwarder: bouncing forwarded mail is wrong.
---------------------------------------------------------------------------------->8
(Co-incidence that the author of that text is the package maintainer for
this package)

Find attached a patch which turns a REJECT into a DISCARD when a
"Precedence: List" header is present.

I took http://mit.edu/network/spam/examples/britney.txt and pre-pended a
  "Precendence: List" header to it, telneted into the box on 25
EHLO,MAIL FROM,RCPT TO,DATA,<paste> and as result:

Dec 27 15:25:39 abaddon spamd[31168]: spamd: identified spam (11.7/5.0)
for jeroen:108 in 5.1 seconds, 1199 bytes.
Dec 27 15:25:39 abaddon spamd[31168]: spamd: result: Y 11 -
BAYES_60,DATE_IN_PAST_24_48,FH_FROMEML_NOTLD,HTML_MESSAGE,HTML_MISSING_CTYPE,HTML_TAG_BALANCE_BODY,INVALID_DATE,MISSING_MIME_HB_SEP,NORMAL_HTTP_TO_IP,RDNS_NONE
scantime=5.1,size=1199,user=jeroen,uid=108,required_score=5.0,rhost=localhost,raddr=127.0.0.1,rport=9814,mid=<200106110439.AAA06179@pacific-carrier-annex.mit.edu>,bayes=0.790679,autolearn=no
Dec 27 15:25:39 abaddon postfix/cleanup[32588]: 99F0135A523:
milter-discard: END-OF-MESSAGE from
noc.sixxs.net[2001:838:1:1:210:dcff:fe20:7c7c]: milter triggers DISCARD
action; from=<testink@unfix.org> to=<jeroen@unfix.org> proto=ESMTP
helo=<noc.sixxs.net>

Please apply this patch to spamass-milter so that I don't get unsubbed
anymore from Debian mailinglists because they are forwarding spam and spam.

Greets,
 Jeroen

I've also filed it to https://savannah.nongnu.org/support/?106593
in the hope that upstream also applies it directly.

Greets,
 Jeroen

severity 509901 wishlist
tags 509901 patch
retitle 509901 turn REJECT into DISCARD when "Precedence: (list|junk|bulk) header present
clone 509901 -1
reassign -1 clamav-milter
retitle -1 turn REJECT into BLACKHOLE when "Precedence: (list|junk|bulk) header present
tags -1 -patch
thanks

This is a good idea, I think, and also applies to clamav-milter.

+1 from me.

also sprach Jeroen Massar <jeroen@unfix.org> [2008.12.27.1633 +0100]:

This should probably be repeated for Bulk and Junk.

It would be good to have some verbose logging, so that I can look at
verbose or debug logs and figure out why a message was discarded and
not rejected.

Does this patch still apply?

https://lists.debian.org/debian-security/2014/11/msg00040.html

This concept was last mentioned on the debian-security list late last year,
there is still a need for this and it's affecting many people who are involved
in the Debian project.