docs: agree queue-retries (Postfix retry policy in the panel)

Roadmap item and plan: show first retry delay, backoff cap and queue
lifetime on Mail queue and the delivery page, reading postconf -h once
at panel start so a manual override is visible. Explanation only; not
implemented yet. CHANGELOG updated.

Co-Authored-By: Cursor Grok 4.6 <noreply@anthropic.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

CHANGELOG.md

@@ -5,6 +5,15 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/); version
 
 ## [Unreleased]
 
+### Added
+
+- docs: agreed roadmap item **queue-retries** — show this Postfix's retry
+  policy (first delay, backoff cap, queue lifetime) on Mail queue and on a
+  delivery's history, reading `postconf -h` once at panel start so a manual
+  override is visible. Plan: [docs/plans/queue-retries.md](docs/plans/queue-retries.md).
+  Explanation only; no attempt counter and no panel knobs. Not yet
+  implemented.
+
 ### Fixed
 
 - test (e2e): send-log status scrapers follow the badge markup in

docs/plans/queue-retries.md

@@ -0,0 +1,142 @@
+# Plan: queue-retries (Postfix retry policy in the panel)
+
+**Status:** agreed  
+**Date:** 2026-08-13  
+**Version:** patch; no schema, no configuration surface.  
+**Order:** small panel item; does not wait on inbound-relay. May follow or
+interleave with remaining [code-review.md](code-review.md) work after P0.
+
+---
+
+## Goal
+
+Show the operator how Postfix retries deferred mail: first retry delay, later
+backoff cap, and how long a message stays in the queue before it bounces. The
+numbers come from this container's effective Postfix config, not from
+hard-coded copy.
+
+## Scope
+
+**In:**
+
+- A static «How delivery retries work» card on `/mail-queue` (global
+  administrator). Not inside the HTMX poll fragment — the snapshot is taken at
+  panel start.
+- The same human-readable intervals in `/deliveries/{id}` history for
+  `deferred` and `bounced` (domain administrators never see Mail queue).
+- Operator docs: [guide.md](../guide.md) Mail queue bullet;
+  [architecture.md](../architecture.md) notes the one-shot `postconf -h` at
+  panel start. [CHANGELOG.md](../../CHANGELOG.md) `### Added`.
+
+**Out:**
+
+- Changing Postfix retry parameters, or exposing them as panel settings
+  ([product.md](../product.md): Postfix is used as-is).
+- An `attempts` column on `send_log`, or «attempt 3 of N» — Postfix has no
+  attempt budget; it is time-based.
+- Counting `status=deferred` lines in `mail.log` or reading `postcat`. Each
+  attempt is already on the delivery page's log table; the journal stores only
+  the last status.
+- Duplicating the card on Status (summary + link to Mail queue already exist).
+- Re-reading `postconf` on every HTTP request.
+
+## Architecture
+
+Acceptance is still synchronous SMTP. Delivery stays in Postfix's on-disk
+queue. SelfPost does not enqueue, retry, or deliver.
+
+```mermaid
+flowchart LR
+  smtpAccept["SMTP 250 accepted"] --> postfixQueue["Postfix queue"]
+  postfixQueue -->|"deferred: backoff until queue lifetime"| retry["Retry MX"]
+  retry -->|sent| done["sent"]
+  retry -->|lifetime elapsed or 5xx| bounce["bounced"]
+  postfixQueue --> mailQueuePage["/mail-queue policy card"]
+  postfixQueue --> deliveryPage["/deliveries/id history copy"]
+```
+
+[build/postfix-config.sh](../../build/postfix-config.sh) does not set
+`queue_run_delay`, `minimal_backoff_time`, `maximal_backoff_time`,
+`maximal_queue_lifetime`, `bounce_queue_lifetime`, or `delay_warning_time`.
+Debian/Postfix 3.x compiled-in defaults therefore apply unless the operator
+overrides them (`postconf -e` inside the container).
+
+### Loading the numbers
+
+Once, when the HTTP role starts ([cmd/panel/httpserver.go](../../cmd/panel/httpserver.go),
+after `postfix-config.sh` has run):
+
+```
+postconf -h queue_run_delay minimal_backoff_time maximal_backoff_time maximal_queue_lifetime bounce_queue_lifetime delay_warning_time
+```
+
+`postconf -h`, not a parse of `/etc/postfix/main.cf`: stock values are not
+written to the file. `postconf` is the effective config, including a manual
+override.
+
+- Fixed argv, no user input — same pattern as
+  [postfix.Queue](../../internal/postfix/queue.go) /
+  [security.md](../security.md).
+- Cache on `handlers.Config` (via `web.Config`). The HTMX fragment does not
+  call `postconf`.
+- A live `postconf -e` is visible after the next panel (or container) restart.
+  While the process is up, the panel shows the start-up snapshot.
+- Parse Postfix time units (`300s`, `5d`, `1h`, a bare number is seconds) in
+  `internal/postfix`. Format human strings (`5 minutes`, `5 days`,
+  `about 1 hour 7 minutes`) in one place so the Mail queue card and
+  `deliveryEvents` cannot drift.
+- If `postconf` is missing (unit tests on Windows, binary outside the
+  container): log a warning, fall back to Postfix 3.x compiled-in defaults
+  (`300s` / `4000s` / `5d` / `0`), and put a muted note on the card. Tests
+  stub the lookup (as `queueIDs` in the log-tailer) or pass a fixture on
+  `Config`. Do not fail panel start.
+
+Typical stock values, for orientation only — the UI prints whatever
+`postconf` returned:
+
+| Parameter | Stock | Meaning |
+|---|---|---|
+| `queue_run_delay` / `minimal_backoff_time` | `300s` | First retry and deferred-queue scan |
+| `maximal_backoff_time` | `4000s` | Cap on the doubling gap (~1 h 7 min) |
+| `maximal_queue_lifetime` | `5d` | Then bounce |
+| `delay_warning_time` | `0` | No delay warning to the sender |
+
+## Panel copy
+
+Mail queue card facts: first retry; later retries (doubling, capped);
+kept in queue; then bounced. Short prose: there is no fixed attempt count; a
+`deferred` message stays in this listing until it is delivered or the queue
+lifetime runs out.
+
+`deliveryEvents(row, policy)`:
+
+- `deferred`: retries, first after X, then with increasing gaps up to Y, for
+  up to Z.
+- `bounced`: or Postfix gave up after Z in the queue.
+
+## Tests
+
+- Duration parser: `5d`, `300s`, `4000s`, `1h`, `0`, bare number.
+- `/mail-queue` handler: card shows the fixture policy's human strings, not a
+  live `postconf`.
+- Delivery page / `deliveryEvents`: `deferred` and `bounced` contain those
+  strings ([handlers_monitor_test.go](../../internal/web/handlers/handlers_monitor_test.go)).
+- [templates_test.go](../../internal/web/view/templates_test.go): pass the new
+  fields if rendering `mail_queue` requires them.
+
+`go test` / `go vet` on the touched packages.
+
+## Done when
+
+- `/mail-queue` states this Postfix's first retry, backoff cap, and queue
+  lifetime.
+- A `deferred` / `bounced` delivery page uses the same intervals.
+- A manual `postconf -e maximal_queue_lifetime=2d` followed by a panel restart
+  changes what the panel prints.
+- Guide and architecture describe the snapshot; CHANGELOG has an Added entry.
+
+## Risks
+
+- Showing compiled-in fallbacks when `postconf` failed would mislead if the
+  operator had overridden them — mitigate with the muted note on the card.
+- Inventing a max-attempt count would be false; the copy must stay time-based.

docs/roadmap.md

@@ -29,6 +29,7 @@ in `git log` and [CHANGELOG.md](../CHANGELOG.md).
 | ID | Topic | Status | Plan |
 |---|---|---|---|
 | code-review | Full-tree review follow-ups (authz, docs, GUI, tests) | **agreed** | [plans/code-review.md](plans/code-review.md) |
+| queue-retries | Postfix retry policy in the panel (queue lifetime, backoff) | **agreed** | [plans/queue-retries.md](plans/queue-retries.md) |
 | inbound-relay | Inbound relay (backup-MX / forwarding) | **agreed** | [plans/inbound-relay.md](plans/inbound-relay.md) |
 | contributing | `CONTRIBUTING.md` | candidate | — |
 | dmarc-reports | DMARC aggregate report ingestion and panel UI | candidate | [plans/dmarc-reports.md](plans/dmarc-reports.md) |
@@ -37,7 +38,8 @@ in `git log` and [CHANGELOG.md](../CHANGELOG.md).
 
 **Recommended order** (not binding): **code-review P0** first (shipped
 domain-admin send-log leak — a defect, not a feature), then the rest of that
-plan as listed, then **inbound-relay**. Candidates need explicit agreement
+plan as listed; **queue-retries** is a small panel item that can land in
+parallel after P0; then **inbound-relay**. Candidates need explicit agreement
 before they join the queue.
 
 After a context reset, pick an item marked `agreed` or `in progress`, then work
@@ -64,6 +66,27 @@ jumps the feature queue. Implementation models are in the plan (Opus / Sonnet
 
 ---
 
+## queue-retries
+
+**Goal:** show on Mail queue and on a delivery's history how this Postfix
+retries deferred mail — first delay, backoff cap, queue lifetime — reading
+the effective config (`postconf -h`) once at panel start so a manual
+override is visible.
+
+**Boundary:** explanation only. Postfix stays as-is; no attempt counter, no
+panel knobs for queue lifetime, no schema change. Domain administrators see
+the intervals on `/deliveries/{id}` (they cannot open Mail queue).
+
+**Done when:** see the criteria in
+[plans/queue-retries.md](plans/queue-retries.md).
+
+**Dependencies / risks:** `postconf` unavailable outside the container
+(fallback + muted note). Copy must stay time-based — Postfix has no max
+attempt count.
+**Version:** patch.
+
+---
+
 ## inbound-relay
 
 **Goal:** optional acceptance of mail on port 25 for explicitly configured