mixandClaude Opus 5.5
60c7b85f84
Technical review (Opus) and security review (Fable) of 9efc9c7..a59e3d4; reports in the session's scratchpad. Fixed: - B1 (verified bug): store.UpdateStatus read before writing in its transaction; a commit by another connection in between (the dmarc-ingest process opens the same file) failed it at once with "database is locked" and the delivery line was lost. The first statement is now a write. - R3: a delivery line updated every row of its queue id and recipient; it now updates only the newest (Postfix reuses short ids). The sweep closes by row id (QueuedDelivery.ID, CloseUnreported(id)). - R4: a contradicted sweep keeps a mark, reason "reconcile-contradicted", instead of losing which row it was. - R1: contradicted cannot see a lost line (never read late). New counter reconcile_missed: at close, the sweep looks for the row's delivery line in mail.log and mail.log.1 (QueueLines). 0007 edited - it has run on no database but throwaway stands. - R2: queued_over_lifetime cannot measure "what removing the sweep would leave" while the sweep runs; its text now says rows stuck despite the sweep, and the rule uses closed - missed - contradicted. - cert-reload (R5, R6, R7, security medium/low): both files copied to .new and the copies checked as a pair before both are renamed; acts on the copy only when postconf says Postfix reads it; a failed reload is retried next pass; umask 077; says so when the mounted files cannot be read. The e2e case asserts Postfix reads the copy, the copy equals the mount, the key is 600 root. - Security low: a recipient with a quoted local part - the journal cut "a b"@x at the space, deliveryRe cut "a>b"@x at the ">" - matched no delivery line and was closed by the sweep. cleanAddress ends a bracketed address at the first ">" outside quotes; deliveryRe takes the recipient up to the ">, " before relay= (test fixtures given the relay= every real delivery line has). - Security low: postqueue -p's error carries at most 512 bytes of output. - Nits: addDeliveryLogDay refuses a column not on its list; the truncation test checks its message. - To stage 2b (page wording, mockup-first): the history step of a bounced row says the receiving server refused it, false for a row the sweep closed. To the owner when stage 2b is reached: since M13 the "deferred" figure counts whole messages too, which "Connections turned away" would not name. Found while verifying: the e2e's main positive path failed once with "553 not owned by user app1" - an smtpd idle from before the panel's reload took the connection in the reload's second. Measured on the stand (one-off probe, not committed): sending 0, 10, 40, 110 s after the save (two seconds at the soonest) always met an smtpd started after the reload. The e2e now waits for the sender map after each application it creates (waitForSenderMap: AUTH, MAIL, RCPT, RSET - no message, no row), and the level-1 case uses it instead of its own loop. Docs: architecture § Queue reconcile, schema-migrations (rows 7 and 8, chain head 8), CHANGELOG, audit plan (stage 1 note, the measured window, a new stage 2b line: 62 lines), roadmap 15/62. Evidence on the test server for this tree: go vet clean, go test ./... 23 packages ok, make e2e exit 0 (renewed certificate, hung panel, level 1 at 49/60). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
SelfPost
Self-hosted SMTP relay with a web panel — one Docker image, no provider.
Postfix, OpenDKIM, and a small Go panel run together under supervisord; you
configure domains, DKIM keys, and SASL applications once, then point your apps
at the SMTP endpoint.
SelfPost sends mail straight to the internet from your own IP, with per-domain DKIM signing. No mailboxes or webmail. An optional inbound relay (backup-MX / forwarder on port 25) forwards to an upstream; it does not store mail.
For: operators who run their own VPS or home server and want a simple relay they control, without a third-party SMTP provider.
Key properties: one container, multi-domain DKIM, SASL per application, send log and DNS checks in the panel, encrypted backups.
Features
- Outbound SMTP (465/smtps; optional 587 submission) with per-domain DKIM signing
- Optional inbound relay on port 25 (backup-MX / forwarder; off by default)
- Optional DMARC aggregate report ingest on port 25 (off by default)
- In-panel Help: a page of topics, opened from the
?in the head of a box - Per-application client IP allow-list for SMTP AUTH (optional)
- Web panel grouped by mail direction — Overview, Outbound (domains, log, queue, DMARC reports), Inbound, Server (health, system log, backup, users, settings)
- Multi-domain relay — each SASL application is bound to one sending domain
- DNS status checks (PTR, SPF, DKIM, DMARC) with in-panel re-check
- Two-level rate limiting — IP backstop (Postfix), per-domain ceilings, and trusted-IP app overrides
- Full-server backup and single-domain export/import (optional password encryption)
- Single Docker image; production data in a
./databind mount (the quick start below uses a named Docker volume instead)
Documentation
| Document | Contents |
|---|---|
| Operator guide | Reverse proxy, environment variables, DNS, IP warmup, panel operations, rate limiting, backup/restore, ports, image tag |
| Product boundaries | Purpose, deployment assumptions, out-of-scope items, multi-domain model |
| Architecture | As-built technical design |
| Security design | Mandatory requirements, accepted risks, the CSRF ADR |
| Development | Building, testing, docs rules, model routing, commits |
| Roadmap | Open work (1.x+) — direction, not commitments |
| CHANGELOG | Release history |
Found a vulnerability? Do not open an issue — SECURITY.md has the private reporting channel and the scope.
Repository: https://github.com/mixeme/selfpost — source, issues, releases, and
the ghcr.io/mixeme/selfpost image.
Requirements
Providing these is the operator's job — SelfPost cannot fix a blocked port or a missing PTR record for you. Details: Operator guide.
Platform
- Docker + Compose v2 on the host
- A reverse proxy in front of the panel (SelfPost never terminates HTTPS itself)
- Rough sizing: 1 vCPU, 512 MB–1 GB RAM, 8–10 GB disk (send log and
rotated
mail.logare the main growth drivers; both sit in the./datavolume, and both are capped — 90 days and 14 files by default)
Network and IP
- Static IP address
- Outbound TCP port 25 unblocked (many consumer/cloud hosts block it by default)
- PTR/rDNS for that IP pointing at your mail hostname (
SELFPOST_HOSTNAME) - Reasonable starting IP reputation — a fresh IP still needs warmup
Per sending domain
For every domain you add in the panel:
- SPF TXT record authorizing this server
- DKIM TXT record (value shown on the domain page)
- DMARC
_dmarcTXT record
See Domain-level DNS in the operator guide.
Per inbound domain (optional)
Only if you turn on inbound relay (INBOUND_RELAY_ENABLE=true):
- MX record pointing at
SELFPOST_HOSTNAME(keep any existing primary MX if this host is backup-MX)
See Inbound relay in the operator guide.
Quick start
First boot — create the admin account. On a fresh container SelfPost prints a one-time setup URL (valid ten minutes). Open it in a browser to choose the administrator username and password. Until you do, the panel has no login. Production deploy: Full deployment in the operator guide.
One container, panel at http://127.0.0.1:8080 — no reverse proxy, no TLS
files, no compose files. Good for clicking through the UI on your machine;
outbound mail will not reach the real internet without DNS, PTR, and port 25.
The 2.x line is not published on ghcr.io yet (the newest image there is
1.3.0). Until it is, build the image from this checkout under the name the commands below anddeploy/docker-compose.ymluse; Docker then takes the local image and pulls nothing:docker build -f build/Dockerfile --build-arg VERSION=2.4.2 \ -t ghcr.io/mixeme/selfpost:2.4.2 .
docker run --rm -d --name selfpost-try \
-p 127.0.0.1:8080:8080 \
-e SELFPOST_HOSTNAME=mail.local.test \
-e PANEL_COOKIE_SECURE=false \
-v selfpost-try-data:/data \
ghcr.io/mixeme/selfpost:2.4.2
Get the setup URL (pick one):
docker logs selfpost-try 2>&1 | grep -m1 'http'
docker exec selfpost-try cat /data/setup-token
The printed URL is https://mail.local.test/setup/<token>. For this local
trial rewrite it to http://127.0.0.1:8080/setup/<token> (same path token;
PANEL_COOKIE_SECURE=false so the cookie works over plain HTTP). Open it
before it expires.
When finished:
docker rm -f selfpost-try && docker volume rm selfpost-try-data
More detail (limitations, optional throwaway TLS for local SMTP): Local trial in the operator guide.
Reference deploy
Production layout: one docker-compose.yml, a .env, persistent ./data, and
TLS PEM files at ./certs (read by Postfix on 465/587). The panel is reached
only through a reverse proxy on 443 — port 8080 is bound to localhost in the
default compose file.
Full walkthrough — fetching the base files, setting up a reverse proxy and TLS (Apache/nginx/Caddy/Traefik), starting the container, and wiring up DNS — lives in the operator guide's Full deployment section, with proxy-specific commands under Reverse proxy.
The compose file always publishes 465, 587, and 25; Postfix listens
on 587 only when SUBMISSION_ENABLE=true, and on 25 when
INBOUND_RELAY_ENABLE=true and/or DMARC_REPORTS_ENABLE=true (see
Ports). Bump the
pinned image tag deliberately when upgrading, never :latest (why). Optional
variables (TRUSTED_PROXY_CIDR, rate limits, retention): see Environment
variables.
License
Copyright © 2026 Mikhail Yenuchenko.
AGPL-3.0. The AGPL closes the "SaaS loophole": if you run a modified version as a network-accessible service, you must make the modified source available to its users — not only when you distribute copies of the code. Third-party notices: NOTICE.