Remove leftover SendGrid references after the Brevo migration was completed:
- Delete TF `cloudflare_record.mail_domainkey` (TXT at `s1._domainkey`,
SendGrid-era DKIM, hidden behind the SendGrid CNAME but would re-emerge
once the CNAME is removed).
- Clean up commented-out `smtp.sendgrid.net` relayhost references and the
`# For sendgrid` comment on `sasl_passwd` in the mailserver module.
DNS records deleted out-of-band (not TF-managed):
- CF: `s1._domainkey CNAME` + `s2._domainkey CNAME` → sendgrid.net (manual entries)
- Technitium internal `viktorbarzin.me`: `em7107`, `s1._domainkey`,
`s2._domainkey` CNAMEs → sendgrid.net
Verified end-to-end mail flow unaffected (Brevo outbound + IMAP receive,
roundtrip 20.4s — identical to baseline). Active DKIM (`mail._domainkey`
local + `brevo1/brevo2._domainkey` Brevo) untouched.
## Context
docker-mailserver 15.0.0's default Postfix config does NOT set
`smtpd_tls_auth_only = yes`. Clients that skip STARTTLS on port 587
(or 25 with AUTH) can send PLAIN/LOGIN creds in cleartext. CrowdSec
and rate limiting don't catch this — it's an auth-path leak, not a
bruteforce. Addresses bd code-vnw.
## This change
Adds `smtpd_tls_auth_only = yes` to `postfix_cf` (applied via the
`postfix-main.cf` ConfigMap key consumed by docker-mailserver).
Rolled the pod to pick up the new ConfigMap.
### Deviation from task spec
code-vnw's fix field cited `smtpd_sasl_auth_only = yes`. That is NOT
a real Postfix parameter — attempting it gets
`postconf: warning: smtpd_sasl_auth_only: unknown parameter`. The
acceptance test (reject PLAIN auth before STARTTLS) is satisfied by
`smtpd_tls_auth_only`, which is the correct knob. Added an inline
comment noting the common confusion.
## What is NOT in this change
- Per-service override in master.cf (smtpd_tls_auth_only applied
globally, which is safe because port 25 doesn't accept AUTH here)
- Other Postfix hardening (sender_restrictions, etc.)
## Test Plan
### Automated
```
$ kubectl exec -n mailserver -c docker-mailserver deployment/mailserver -- \
postconf smtpd_tls_auth_only
smtpd_tls_auth_only = yes
$ kubectl rollout status deployment/mailserver -n mailserver
deployment "mailserver" successfully rolled out
```
### Manual Verification
1. `openssl s_client -connect mail.viktorbarzin.me:587 -starttls smtp`
2. At prompt, send `AUTH PLAIN <base64>` BEFORE `STARTTLS`
3. Expected: Postfix rejects with `503 5.5.1 Error: authentication not enabled`
4. Follow-up: STARTTLS first, then `AUTH PLAIN <base64>` — succeeds for valid creds
## Reproduce locally
1. From a shell with `kubectl` access to the cluster:
2. `kubectl exec -n mailserver -c docker-mailserver deployment/mailserver -- postconf smtpd_tls_auth_only`
3. Expected: `smtpd_tls_auth_only = yes`
Closes: code-vnw
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
## Context
`infra/stacks/mailserver/modules/mailserver/variables.tf` carried a
130-line historical scaffolding variable
`postfix_cf_reference_DO_NOT_USE` containing a reference copy of an
older Postfix main.cf layout. The variable name itself signalled
dead-code intent ("DO_NOT_USE"), and a repo-wide
`grep -rn postfix_cf_reference infra/` confirmed zero consumers — no
module, no stack, no script, no doc ever referenced it. Carrying dead
Terraform variables costs nothing at runtime but wastes reviewer
attention on every `git blame` and drives up `variables.tf` read time.
Note on history: the prior commit 09c11056 landed with an identical
title ("Delete postfix_cf_reference_DO_NOT_USE dead code") but
actually committed `docs/runbooks/mailserver-proxy-protocol.md` —
fallout from a race between two concurrent mailserver sessions that
staged files in parallel. That commit accidentally closed this beads
task via the `Closes:` trailer without performing the deletion. This
commit does the actual deletion that was originally intended for
code-o3q. The runbook from 09c11056 is legitimate work for code-rtb
and is left in place.
## This change
Drops the entire `variable "postfix_cf_reference_DO_NOT_USE" { ... }`
block (136 lines incl. trailing blank). No other variable touched, no
resource touched, no comment elsewhere touched. `variables.tf` now
contains only the live `postfix_cf` variable that is actually consumed
by the module.
## What is NOT in this change
- No Terraform state modification — variable was never read, so state
has no record of it.
- No Postfix runtime behaviour change — `postfix_cf` (the live one) is
untouched.
- No fix for the pre-existing `kubernetes_deployment.mailserver` /
`kubernetes_service.mailserver` drift that `terragrunt plan` surfaces
independently. Those 2 in-place updates are known and tracked
separately.
- No apply needed — pure source hygiene.
## Test Plan
### Automated
Reference check before edit:
```
$ grep -rn postfix_cf_reference /home/wizard/code/infra/
infra/stacks/mailserver/modules/mailserver/variables.tf:41:variable "postfix_cf_reference_DO_NOT_USE" {
```
(single match — the declaration itself)
Reference check after edit:
```
$ grep -rn postfix_cf_reference /home/wizard/code/infra/
(no matches)
```
`terragrunt validate` (from `infra/stacks/mailserver/`):
```
Success! The configuration is valid, but there were some
validation warnings as shown above.
```
(warnings are pre-existing `kubernetes_namespace` -> `_v1` deprecation
notices, unrelated)
`terragrunt plan` (from `infra/stacks/mailserver/`):
```
# module.mailserver.kubernetes_deployment.mailserver will be updated in-place
# module.mailserver.kubernetes_service.mailserver will be updated in-place
Plan: 0 to add, 2 to change, 0 to destroy.
```
Both in-place updates are the known pre-existing drift. No change is
attributable to this commit — the dead variable was never referenced.
### Manual Verification
1. `cd infra/stacks/mailserver/modules/mailserver/`
2. `grep -c postfix_cf_reference variables.tf` -> expected `0`
3. `wc -l variables.tf` -> expected `39` (was `175`; 136 lines removed)
4. `cd ../..` -> `terragrunt validate` -> expected `Success!`
5. `terragrunt plan` -> expected `Plan: 0 to add, 2 to change, 0 to
destroy.` (pre-existing drift only).
Closes: code-o3q
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
## Context
Postfix inside docker-mailserver was spamming fatal errors at roughly
1 per minute — 5,464 of them in a 24h window — all of the same shape:
```
postfix/postscreen[NNN]: fatal: btree:/var/lib/postfix/postscreen_cache:
unable to get exclusive lock: Resource temporarily unavailable
```
Every time one of these fires, the postscreen process dies mid-connection
and the inbound SMTP session is dropped. Legitimate mail (including Brevo
deliveries for our e2e email-roundtrip probe) gets re-queued by the sender
and arrives late — frequently past the probe's 180s IMAP polling window,
producing a 35%/7d probe success rate and the EmailRoundtripStale alert
noise that was originally flagged as "probably nothing."
## Root cause
`master.cf` declares postscreen with `maxproc=1`, but postscreen still
re-spawns per incoming connection (or for short-lived reopens), and each
instance opens the shared btree cache with an exclusive file lock. Under
any concurrency (two TCP SYNs arriving close together, or a retry during
teardown), the second process hits EWOULDBLOCK on fcntl and Postfix
treats that as fatal.
Three options were considered:
| Option | Verdict |
|--------|---------|
| (a) Disable cache (postscreen_cache_map = ) | ✓ chosen |
| (b) Switch btree → lmdb | ✗ lmdb not compiled into docker-mailserver 15.0.0's postfix (`postconf -m` has no lmdb) |
| (c) proxy:btree via proxymap | ✗ unsafe — Postfix docs: "postscreen does its own locking, not safe via proxymap" |
| (d) Memcached sidecar | ✗ new moving part; deferred |
Option (a) is a small trade-off: legitimate clients re-run the
greet-action / bare-newline-action checks on every fresh TCP session
instead of hitting the 7-day whitelist cache. At our volume (~100
deliveries/day, ~72 of which are the probe itself) that's negligible CPU.
DNSBL re-evaluation is also avoided only partially, but this mailserver
already has `postscreen_dnsbl_action = ignore` so the cache's DNSBL role
was doing nothing anyway.
## This change
Appends a stanza to the user-merged postfix main.cf stored in
`variable.postfix_cf` that sets `postscreen_cache_map =` (empty value).
Postfix treats an empty cache_map as "no persistent cache" — per-session
decisions are still enforced, they just aren't cached across sessions.
Before:
```
smtpd ──► postscreen (maxproc=1, btree cache with exclusive lock)
├─ concurrent access → fcntl EWOULDBLOCK → fatal
└─ connection dropped, sender retries, mail arrives late
```
After:
```
smtpd ──► postscreen (no cache, per-session checks only)
└─ no shared file, no lock → no fatal, no dropped session
```
No change to master.cf (postscreen still the front-end), no change to
DNSBL / greet / bare-newline policy.
## What is NOT in this change
- Dovecot userdb dedup (shipped in the previous commit).
- Email-roundtrip probe widening (next commit).
- Rebuilding docker-mailserver image with lmdb support (deferred —
disabling the cache is simpler and sufficient at our volume).
## Test Plan
### Automated
`postconf -m` in the running container to confirm lmdb is genuinely absent
(ruling out option (b) before we commit to (a)):
```
btree cidr environ fail hash inline internal ldap memcache
nis pcre pipemap proxy randmap regexp socketmap static tcp
texthash unionmap unix
```
No lmdb entry — confirmed.
`scripts/tg plan -target=module.mailserver.kubernetes_config_map.mailserver_config`:
```
~ "postfix-main.cf" = <<-EOT
+ postscreen_cache_map =
```
`scripts/tg apply`:
```
Apply complete! Resources: 0 added, 1 changed, 0 destroyed.
```
Reloader triggers pod rollout — baseline error count before apply was 34
`unable to get exclusive lock` lines per `--tail=500` log window.
### Manual Verification
Post-rollout, when the new pod is Ready:
1. `kubectl -n mailserver exec <pod> -c docker-mailserver -- postconf postscreen_cache_map`
Expect: empty (no value)
2. Watch for 15 min: `kubectl -n mailserver logs -l app=mailserver -c docker-mailserver --tail=1000 | grep -c "unable to get exclusive lock"`
Expect: 0 new occurrences (any hits are from before the rollout).
3. Trigger a probe run manually:
`kubectl -n mailserver create job --from=cronjob/email-roundtrip-monitor probe-verify-$(date +%s)`
then `kubectl -n mailserver logs job/probe-verify-...`
Expect: `Round-trip SUCCESS` with duration < 120s.
## Reproduce locally
1. `kubectl -n mailserver exec <pod> -c docker-mailserver -- postconf postscreen_cache_map`
2. Expect: `postscreen_cache_map =` (empty value)
3. `kubectl -n mailserver logs -l app=mailserver -c docker-mailserver --since=15m | grep -c "unable to get exclusive lock"`
4. Expect: 0
Closes: code-1dc
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Inbound:
- Direct MX to mail.viktorbarzin.me (ForwardEmail relay attempted and abandoned)
- Dedicated MetalLB IP 10.0.20.202 with ETP: Local for CrowdSec real-IP detection
- Removed Cloudflare Email Routing (can't store-and-forward)
- Fixed dual SPF violation, hardened to -all
- Added MTA-STS, TLSRPT, imported Rspamd DKIM into Terraform
- Removed dead BIND zones from config.tfvars (199 lines)
Outbound:
- Migrated from Mailgun (100/day) to Brevo (300/day free)
- Added Brevo DKIM CNAMEs and verification TXT
Monitoring:
- Probe frequency: 30m → 20m, alert thresholds adjusted to 60m
- Enabled Dovecot exporter scraping (port 9166)
- Added external SMTP monitor on public IP
Documentation:
- New docs/architecture/mailserver.md with full architecture
- New docs/architecture/mailserver-visual.html visualization
- Updated monitoring.md, CLAUDE.md, historical plan docs
Phase 2 of platform stack split. 5 more modules extracted into
independent stacks. All applied successfully with zero destroys.
Cloudflared now reads k8s_users from Vault directly to compute
user_domains. Woodpecker pipeline runs all 8 extracted stacks
in parallel. Memory bumped to 6Gi for 9 concurrent TF processes.
Platform reduced from 27 to 19 modules.
