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inbound-antispam-panel: refused inbound mail from mail.log; retention

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Step 4/12 of docs/plans/inbound-antispam-panel.md.

The log tailer writes an inbound_spam_log row for mail port 25 refused
(internal/logtail/inbound.go): a "reject:" line of the port-25 smtpd is
Postfix's own policy; a milter-reject / milter-hold / milter-discard
line of cleanup is the filter's verdict. Only a recipient at an inbound
domain is a row, so "Relay access denied" for a stranger's domain is
not. The row is dated by its log line; the reply text is cut to 255
bytes of printable ASCII; a reply starting with 4 is a tempfail.

To tell port 25 from 465 / 587 the listener now logs as
postfix/inbound (syslog_name). cleanup logs under one name for every
listener, so its verdict counts only for a queue id the port-25 smtpd
was seen to open (4096 remembered). Lines are matched from the head,
after timestamp and host: their tail is the sender's own text.

Retention: PruneInboundSpam every six hours - older than the
inbound_spam_log_retention_days setting (seeded from
INBOUND_SPAM_LOG_RETENTION_DAYS, 90, range 7-365), then down to 10 000
rows. The setting has no field in the panel yet.

Known limits, in architecture.md: a log line names one recipient, so a
message refused at end-of-message is one row; a line re-read after an
unclean stop would be a second row.

Checked on the test server, uncommitted tree: go vet ./... ok,
go test ./... ok (22 packages), make e2e ok - the unknown recipient at
the inbound domain refused on port 25 has its row (reject by postfix),
the stranger's domain has none.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
mix
2026-10-11 22:42:25 +03:00
co-authored by Claude Opus 5.5
parent 94e94490af
commit 27fd355e53
18 changed files with 744 additions and 25 deletions
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@@ -209,6 +209,7 @@ expected to set; defaults match the code exactly.
| `DMARC_MESSAGE_SIZE_LIMIT` | Maximum report message size in bytes when DMARC ingest is on. | `5242880` (5 MiB) | `.env` |
| `INBOUND_ANTISPAM_MILTER` | Optional milter on the inbound relay listener only (requires `INBOUND_RELAY_ENABLE=true`; not 465/587 or DMARC-only port 25). Empty = off. Format `inet:host:port` or `unix:/path`. Example with [deploy/antispam/docker-compose.antispam.yml](../deploy/antispam/docker-compose.antispam.yml): `inet:antispam:11332`. The panel reads it to report on the *Spam filter* box of the inbound pages and to check that the filter answers (Server › Health). | *(empty)* | `.env` |
| `INBOUND_ANTISPAM_MILTER_ACTION` | What Postfix does if that milter is down: `accept` (fail-open) or `tempfail` (defer). The *Spam filter* box states which. | `accept` | `.env` |
| `INBOUND_SPAM_LOG_RETENTION_DAYS` | How long the inbound journal keeps a row, 7-365 days; it also never holds more than 10 000 rows. Seeds the setting on the first start with the inbound relay on. | `90` | `.env` |
| `INBOUND_JOURNAL_MILTER_SOCKET` | Unix socket of the panel's inbound journal milter, the last milter on port 25 while the inbound relay is on. It records accepted inbound mail and never refuses any; there is no reason to change it. | `/run/selfpost/inbound-journal.sock` | compose |
| `INBOUND_RATE_LIMIT_MESSAGES_PER_IP` | Coarse per-client-IP cap on inbound smtpd (`smtpd_client_message_rate_limit`). Uses the same window as `RATE_LIMIT_WINDOW_SECONDS`. | `20` | `.env` |
| `INBOUND_MESSAGE_SIZE_LIMIT` | Maximum message size in bytes on inbound smtpd (`message_size_limit`). When both inbound relay and DMARC ingest are on, the shared listener uses the **greater** of this and `DMARC_MESSAGE_SIZE_LIMIT`. | `26214400` (25 MiB) | `.env` |