selfpost/docs/plans/inbound-antispam-panel.md

Plan: inbound-antispam-panel

Status: agreed
Date: 2026-08-19
Version: 1.10.0 MINOR (opt-in; no change to outbound-only or inbound-without-filter paths).

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Goal

Give the operator a panel view of inbound anti-spam decisions and editable allow/deny lists that tune filter behaviour — without SelfPost shipping or starting an anti-spam engine (product.md out-of-scope list unchanged).

Typical journal row:

When	From	To	Subject	Decision
2026-08-19 09:14	spammer@evil.example	user@inbound.example	Cheap pills	reject (rspamd: BAYES_SPAM +0.95)

Lists let the operator correct false positives/negatives (e.g. always allow billing@vendor.example, block 192.0.2.0/24).

Context (as-built)

• Inbound relay ships in [1.4.0] (INBOUND_RELAY_ENABLE); optional INBOUND_ANTISPAM_MILTER attaches an external filter (documented rspamd sidecar in deploy/antispam/docker-compose.antispam.yml).
• The inbound smtpd has no journal-milter today — only outbound 465/587 writes send_log (architecture.md).
• Inbound UI and handlers are global-administrator only today (requireInbound → requireGlobal).

Quarantine

Not in this plan. Held-mail review/release is tracked separately as roadmap candidate inbound-quarantine. The journal may still record a quarantine decision label when the external filter reports it, without SelfPost storing the message.

DMARC p=quarantine remains unrelated (outbound policy for receivers).

Decisions (closed 2026-08-19)

Capture mechanism

Inbound journal-milter in panel only — no rspamd history API polling in v1. A separate unix socket (INBOUND_JOURNAL_MILTER_SOCKET, default /run/selfpost/inbound-journal.sock) on the inbound smtpd only; fail-open (default_action=accept).

Milter order on port 25 (when antispam is enabled):

smtpd_milters = { antispam, inbound-journal }

Antispam runs first; inbound-journal runs at end-of-message on the accept path and reads rspamd-added headers (X-Rspamd-Action, X-Rspamd-Score, symbol summary when present).

Antispam rejects do not reach end-of-message on the journal milter. v1 also tails mail.log for inbound postfix/smtpd milter-reject / reject lines and inserts journal rows (client IP, envelope from/to when logged, reason text, subject empty if rejected before DATA). DMARC-ingest pipe traffic is out of scope for this tailer.

Journal without INBOUND_ANTISPAM_MILTER

Journal stays on whenever INBOUND_RELAY_ENABLE=true (not tied to the antispam hook). Without an external filter:

• accept rows — message relayed (engine selfpost, detail empty);
• reject / tempfail rows — from the mail.log tailer (Postfix policy, size limit, unknown recipient, etc.).

Panel copy explains that rspamd symbols appear only when the antispam milter is configured.

RBAC

Global administrator only for journal and lists — same as inbound relay. No domain-admin access in v1.

Retention

Mirror send-log retention:

• Settings key inbound_spam_log_retention_days on /settings (global admin).
• Default 90 days; validation 7–365; seed from env INBOUND_SPAM_LOG_RETENTION_DAYS when the setting is missing.
• Prune every 6 hours (same cadence as send-log retention).
• Hard cap 10 000 rows after age prune (drop oldest) — busier than DMARC reports, lighter than unbounded growth.

Allow/deny lists

Topic	Decision
Entry types	sender address, sender domain (@domain suffix), client IP / CIDR
Precedence	deny overrides allow
Scope	instance-wide (not per inbound domain in v1)
Where applied	rspamd map files under /data/antispam/ (allow.map, deny.map); documented compose fragment mounts them into the sidecar
SelfPost pre-check	out of v1 — lists live in rspamd only
Edit access	global administrator only
When inactive	lists editable in the panel but UI warns that sync applies only when INBOUND_ANTISPAM_MILTER is set; postfix reload / rspamd reload documented in guide

List change → atomic map rewrite (same pattern as Postfix maps) → rspamd reload via documented operator step or sidecar SIGHUP in the compose fragment.

Activation

Condition	Behaviour
INBOUND_RELAY_ENABLE=false	no inbound journal milter, no UI, no tables written
inbound on, antispam empty	journal + UI; lists visible but marked inactive for filter sync
inbound on + antispam set	full journal (symbols on accept) + list sync

No separate feature flag beyond inbound relay + existing antispam env vars.

UI

New nav item Inbound spam (or subsection under Inbound) — journal table with filters (decision, domain, date range), list management on the same page or a tab. Mockup: add docs/assets/panel-ui/inbound_spam.html in the panel step.

Schema (migration 0010_inbound_spam_log.sql)

inbound_spam_log

Column	Type	Notes
id	INTEGER PK
inbound_domain	TEXT NOT NULL	recipient domain (from relay_domains)
client_ip	TEXT NOT NULL
from_addr	TEXT NOT NULL	envelope from
to_addr	TEXT NOT NULL	envelope to (one row per recipient)
subject	TEXT NOT NULL	truncated with mailhdr.SubjectMaxRunes (200)
decision	TEXT NOT NULL	accept, reject, tempfail, quarantine
engine	TEXT NOT NULL	rspamd, postfix, selfpost
detail	TEXT NOT NULL	symbol/score summary or log-line reason; may be empty
created_at	TEXT NOT NULL	RFC3339 UTC

Index on (created_at), (inbound_domain, created_at).

inbound_spam_list

Column	Type	Notes
id	INTEGER PK
list_type	TEXT NOT NULL	allow or deny
entry_type	TEXT NOT NULL	address, domain, ip
value	TEXT NOT NULL	normalized entry
note	TEXT NOT NULL	operator comment; default ''
created_at	TEXT NOT NULL

Unique on (list_type, entry_type, value).

Scope

In:

• Schema, store CRUD, retention loop, mail.log tailer extension for inbound rejects.
• Inbound journal-milter (fail-open) + Postfix postfix-config.sh wiring.
• rspamd map sync under /data/antispam/.
• Panel journal + list UI (global admin).
• Full backup includes /data/antispam/ and new SQLite tables.
• Tests; guide.md; architecture.md.

Out:

• Shipping rspamd, ClamAV, or any filter binary inside the SelfPost image.
• Outbound spam filtering.
• inbound-quarantine.md storage/release.
• rspamd rule editing, Bayes training UI, antivirus.
• MIME replay from the panel (metadata only).
• Per-domain lists; domain-admin RBAC.
• rspamd history API polling.

Architecture

flowchart LR
  internet["Internet :25"] --> inbound["Postfix inbound smtpd"]
  inbound --> antispam["External antispam milter optional"]
  antispam --> journalM["inbound-journal milter fail-open"]
  journalM --> upstream["smtp upstream transport"]
  journalM --> sqlite["inbound_spam_log"]
  mailog["mail.log tailer"] --> sqlite
  listsUI["Panel allow/deny lists"] --> maps["/data/antispam/*.map"]
  maps --> antispam
  sqlite --> journalUI["Panel inbound spam journal"]

Security

• Same validation whitelists as inbound relay (security.md).
• Journal rows contain PII — retention and global-admin-only access.
• Inbound journal milter fail-open must not block mail (backup-MX role).
• List map writes injection-safe; deny wins over allow.

Done when

• With inbound relay + antispam sidecar, panel shows accept rows with symbols and reject rows from mail.log tailing.
• Operator can add/remove list entries; a test message reflects allow/deny.
• With antispam hook off, journal still shows Postfix-level decisions; list UI shows inactive sync notice.
• go vet, go test, image build green; guide and architecture updated.

Risks

• rspamd header/symbol format drift — thin parser, pin sidecar tag in compose.
• Journal volume — retention + 10k cap.
• mail.log parse brittleness — unit tests on sample lines; inbound smtpd only.

Dependencies

• inbound-relay.md (shipped).

Model routing (this plan)

Role	Model
All implementation (code, tests, docs)	Composer
Technical review (reviewer ≠ author)	Opus
Security review	Fable

Composer ships each step; Opus reviews the accumulated diff once implementation steps are done (fix loop: Composer addresses Opus findings, Opus re-checks). Fable runs after Opus sign-off.

Implementation checklist

Target version cut: 1.10.0 (MINOR). One commit per step; development.md § Plan checklists.

• Agree journal fields, retention, and RBAC (this plan § Decisions) — Composer
• Migration 0010_inbound_spam_log.sql — Composer
• Inbound journal-milter + Postfix wiring — Composer
• mail.log tailer: inbound reject rows — Composer
• List CRUD + validation + atomic rspamd map sync — Composer
• Panel: journal + lists UI (+ mockup) — Composer
• Backup includes /data/antispam/ — Composer
• Unit + handler tests — Composer
• guide.md, architecture.md — Composer
• go vet, go test, e2e if applicable — Composer
• Technical review of inbound antispam changes — Opus
• Security review inbound antispam path — Fable