antispam: rspamd strips a sender's own verdict for every client

rspamd 3.11.1's milter_headers skips its verdict routines - removes none
of the sender's X-Spamd-Result / X-Rspamd-Action, adds none - for a client
it counts as local (loopback, a unix socket, local_addrs: the private
ranges) or one that authenticated (skip_local, skip_authenticated, both on
by default; milter_headers.lua skip_wanted(), lua_ip.c lua_ip_is_local()).
The custom routine that signs X-SelfPost-Filter is never put through
skip_wanted(), so it signed the sender's own verdict, and Inbound > Log
showed it as rspamd's. Every sender is private when Docker's proxy relays
port 25 from the bridge gateway. Both options set to false.

Tried 2026-10-14 in a throwaway rspamd/rspamd:3.11.1-3 on the test server
(rspamc --ucl, a message carrying its own verdict headers): old config,
from 10.0.0.5 and as an authenticated user, the milter reply removed and
added neither and added the signature; new config, both removed and
rspamd's own added, as from 203.0.113.9.

Also: the sender rules take the envelope only (extract_from = "smtp"; by
default a bounce's From: header is used - tried: a bounce whose From:
domain is denied was refused before, is not now; a denied sender is
refused either way); the image pinned to 3.11.1-3, the build read (3.11 and
3.11.1 move with each rebuild); the prefilter lines no longer read go.
architecture.md and security.md say so. Assumptions C-R7, B-R1, C-R4,
C-R12, C-R5.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

deploy/antispam/rspamd/multimap.conf

@@ -10,10 +10,21 @@
 # internal/inbound writes with.)
 #
 # Deny wins over allow, whichever entries match. A denied sender is refused
-# before anything else is looked at (a prefilter). An allowed one is not
-# accepted outright - rspamd would then let whichever of the two rules ran
-# first decide - but given a weight no spam score outweighs, which a refusal
-# by the deny list still overrides.
+# whatever else is found (the rule's action is a pre-result, below). An
+# allowed one is not accepted outright - rspamd would then let whichever of
+# the two rules ran first decide - but given a weight no spam score
+# outweighs, which a refusal by the deny list still overrides. (rspamd
+# 3.11.1, src/plugins/lua/multimap.lua: every rule is registered as a
+# "normal" symbol, one with an action with the "passthrough" augmentation;
+# no "prefilter" setting is read.)
+#
+# A sender rule looks at the envelope sender only, extract_from = "smtp":
+# by default multimap.lua takes the header From: when the envelope sender is
+# empty (the "from" callback, has_from('smtp') then has_from('mime')), so a
+# bounce would be judged by an address the panel never counts it under
+# (assumptions C-R4). Tried on 2026-10-14 in rspamd/rspamd:3.11.1-3: a
+# bounce whose From: domain is on the deny list was refused by default and
+# is not with this setting; a sender on the list is refused either way.
 #
 # A domain entry is that domain, not its subdomains. (rspamd 3.11.1,
 # src/libserver/maps/map_helpers.c: a hash map is looked up by the whole key,
@@ -34,24 +45,23 @@
 SELFPOST_DENY_IP {
   type = "ip";
   map = "/etc/rspamd/selfpost/deny_ip.map";
-  prefilter = true;
   action = "reject";
   message = "Refused by this server's deny list";
   description = "Client address on the deny list";
 }
 SELFPOST_DENY_FROM {
   type = "from";
+  extract_from = "smtp";
   map = "/etc/rspamd/selfpost/deny_from.map";
-  prefilter = true;
   action = "reject";
   message = "Refused by this server's deny list";
   description = "Sender address on the deny list";
 }
 SELFPOST_DENY_DOMAIN {
   type = "from";
+  extract_from = "smtp";
   filter = "email:domain";
   map = "/etc/rspamd/selfpost/deny_domain.map";
-  prefilter = true;
   action = "reject";
   message = "Refused by this server's deny list";
   description = "Sender domain on the deny list";
@@ -65,12 +75,14 @@ SELFPOST_ALLOW_IP {
 }
 SELFPOST_ALLOW_FROM {
   type = "from";
+  extract_from = "smtp";
   map = "/etc/rspamd/selfpost/allow_from.map";
   score = -100.0;
   description = "Sender address on the allow list";
 }
 SELFPOST_ALLOW_DOMAIN {
   type = "from";
+  extract_from = "smtp";
   filter = "email:domain";
   map = "/etc/rspamd/selfpost/allow_domain.map";
   score = -100.0;