bongo/contrib/testing/README.md

# Local mail protocol fixtures

These fixtures are intentionally bound to loopback and use non-standard ports.
They are development tools, not production configuration.

## Release and sanitizer harnesses

The scripts used for the 0.7 release evidence are kept here rather than as
one-off files in `/tmp`:

- `test-config-tls-material.sh` generates disposable GnuTLS material and
  covers CFG-09/CFG-10 generation, permissions, reuse, and unsafe-input cases.
- `web-direct-tls-smoke.sh` covers the CFG-08 direct Web TLS 1.2/1.3 listener,
  security headers, plain-HTTP rejection, and a mismatched private key.
- `generate-protocol-test-config.py` creates the disposable local protocol
  configuration used by sanitizer sessions.
- `protocol-smoke.py` delivers through authenticated SMTP submission and reads
  the message through IMAP/POP over explicit and implicit TLS.
- `smtp-basic-check.py` exercises the port-25 greeting and the non-delivery
  HELO/EHLO, NOOP, RSET, HELP, VRFY-policy, and QUIT command surface.
- `smtp-submission-auth-check.py` exercises port 587 STARTTLS and port 465
  implicit TLS directly, including the shared GSASL PLAIN and LOGIN
  mechanisms, pre-TLS AUTH rejection, invalid credentials, and repeated
  STARTTLS rejection. It authenticates but does not submit a message.
- `smtp4dev-fixture.py` manages two authenticated, loopback-only external SMTP
  provider fixtures for STARTTLS and implicit TLS. It validates credentials,
  captures messages through smtp4dev's supported REST API, and keeps both
  databases below `/tmp`.
- `smtp-internal-relay-check.py` temporarily lowers the trusted port 26
  limits, verifies allowed and denied source addresses plus connection,
  recipient, message, and byte limits, then restores the exact SMTP
  configuration without committing a message.
- `smtp-internal-normalization-check.py` sends only to the reserved
  `.invalid` namespace through trusted port 26, inspects the real Queue
  routing envelope for ten sender-normalization cases after atomically moving
  each entry to the hold queue, deletes every test entry, and restores the
  exact SMTP configuration.
- `smtp-local-delivery-check.py` authenticates as one disposable local user
  over STARTTLS submission, sends to another local user, verifies the exact
  message in the recipient's Store INBOX, rejects duplicate delivery, and
  removes its Store and Queue fixtures.
- `smtp-client-interoperability-check.py` repeats real delivery with curl,
  swaks, Xeams Email Sender, GNU Mailutils, and paced Telnet input. It covers
  authenticated STARTTLS submission plus unauthenticated local delivery on
  the public and trusted-device listeners. Password-bearing temporary client
  files use mode 0600 and every delivered Store and Queue fixture is removed.
- `smtp-telnet-timeout-check.py` temporarily lowers the SMTP socket timeout,
  proves that idle Telnet connections close on both plain listeners, and
  proves that slow manual `EHLO`, `NOOP`, and `RSET` input resets the timeout
  after each complete command. It restores the SMTP configuration and active
  service before exiting.
- `smtp-stress-timeout-check.py` uses only two simultaneous connections to
  trigger the configurable load threshold. It proves that the first
  connection keeps the normal timeout while newly accepted inbound,
  trusted-device, and submission connections receive the shorter overload
  timeout, then restores the exact configuration and active service.
- `smtp-outbound-opportunistic-tls-check.py` temporarily installs a
  loopback-only DNS resolver and three direct-MX fixtures. It proves encrypted
  delivery when STARTTLS works, plaintext delivery when it is not advertised,
  and a fresh one-time plaintext reconnect after a failed opportunistic TLS
  handshake. To free standard MX port 25, it temporarily moves Bongo's public
  listener to port 10025. It restores the exact SMTP configuration, resolver
  file, Queue fixtures, and original Bongo service state.
- `smtp-required-tls-check.py` uses isolated direct-MX fixtures to prove that
  globally required TLS never falls back after absent or failed STARTTLS. A
  second phase injects RFC 8689 `REQUIRETLS` over an encrypted trusted
  listener and verifies its Queue trace header, outbound `MAIL FROM`
  parameter, encrypted delivery to a capable peer, and non-delivery when a
  peer lacks TLS or `REQUIRETLS`. It has the same resolver, Queue,
  configuration, and service restoration guarantees as the opportunistic
  check.
- `smtp-dane-mta-sts-check.py` creates a disposable ECDSA-signed DNS zone,
  authoritative BIND instance, validating Unbound resolver, HTTPS policy
  host, and eight loopback MX fixtures. It proves DANE-EE delivery with a
  certificate outside the Web PKI, TLSA mismatch deferral, DANE precedence,
  MTA-STS enforce/testing behavior, exact and wildcard MX policy matching,
  and durable cached-policy use while HTTPS is unavailable. The root-only
  fixture backs up and atomically restores `resolv.conf`, the DNS trust-anchor
  file, SMTP Store configuration, Queue entries, generated certificates, and
  the original service state.
- `sendmail-local-submission-check.py` runs as an unprivileged Unix account
  and verifies both `/usr/sbin/sendmail` and GNU `mail` through Bongo's
  restricted, rate-limited local SMTP submission path. It confirms that no
  Bongo system credential is needed and that Bcc is removed.
- `c-literal-length-check.py` audits manually sized string literals passed to
  Bongo connection I/O helpers and rejects lengths that include a trailing
  NUL, truncate a protocol line, or read past the literal.
- `sanitizer-protocol-session.sh` runs that protocol path under ASan/UBSan/LSan
  or TSan and validates clean process shutdown.
- `asan-protocol-session.sh` and `tsan-protocol-session.sh` preserve the two
  explicit entry points used by the original release runs.
- `sieve-validate-no-lsan.sh` is the narrow helper used by the ASan session;
  the Sieve validator remains leak-tested directly by CTest.
- `cpack-stage-smoke.sh` checks imports and required executables from an
  extracted CPack staging tree in a private mount namespace.
- `debian-source-probe.sh` and `debian-libspf2-package-build.sh` preserve the
  disposable Debian container probes used before the complete bundle builder
  was available.
- `setup-wizard-defaults.py`, `config-tui-edit.py`,
  `legacy-config-install.py`, `protocol-diagnostics.py`, and
  `store-diagnostics.py` preserve the remaining interactive and diagnostic
  bring-up tests. Destructive live helpers require an explicit opt-in
  environment variable.
- `mail-dns-live-check.py` logs in through the real Web and IMAPS interfaces
  and verifies that setup produced both an actionable SPF/DKIM/DMARC task and
  a forwardable administrator message without private-key material.
- `dkim-material-check.py` compares a real OpenDKIM-generated RSA-2048 key
  with Bongo's GnuTLS-derived public value, imports it, checks permissions and
  DNS output, then verifies byte-identical reuse.
- `manager-lifecycle-check.sh` exercises systemd reload/restart/stop/start,
  one agent crash, and an unclean manager death which leaves a stale PID file.
  It requires explicit live-test opt-in and restores an active service on exit.
- `agent-privilege-check.sh` verifies the live manager/agent process tree,
  real/effective/saved UID and GID tuples, supplementary groups, and inherited,
  permitted, effective, and ambient capabilities.
- `store-user-layout-check.sh` idempotently provisions disposable Store,
  Queue, quota, and protocol users, then proves that two freshly accessed
  accounts have separate Store databases and the complete standard folder
  layout, including the IMAP `\\Junk` spam collection.
- `store-backup-compare.py` compares backups made before and after a restore.
  It requires byte-identical payloads, paths, GUIDs, flags, IMAP UIDs, custom
  properties, and calendar-link metadata while ignoring only Store-generated
  creation/modification timestamps.
- `store-protocol-safety-check.py` sends unknown, malformed, oversized, and
  unauthorised commands to a live Store listener. It verifies that
  maintenance/debug commands remain manager-only, a user cannot inspect a
  foreign Store, and the listener remains available after every rejection.
- `store-quota-concurrency-check.py` writes oversized contact and calendar
  fixtures without charging mail quota, then races two Store deliveries
  against one remaining quota slot. Exactly one delivery must succeed and the
  other must receive Store status 5220.

The complete mapping from the original one-off `/tmp` names to maintained
scripts is recorded in `tmp-script-map.md`.

Every script which creates credentials requires disposable values through the
environment; no test password or private key is stored in Git. For example:

```sh
export BONGO_TEST_PASSWORD='a-disposable-password-of-at-least-12-characters'
export BONGO_TEST_ROOT=/tmp/bongo-0.7-r1-asan-root/usr
export BONGO_SANITIZER=asan
unshare --user --map-root-user --net \
  ./contrib/testing/sanitizer-protocol-session.sh
```

## Local protocol-test PKI

Gentoo's `app-misc/ca-certificates` package imports administrator-provided
PEM certificates with a `.crt` suffix from
`/usr/local/share/ca-certificates`. The reusable test-PKI helper creates two
independent roots. Only `Bongo Local Test Root CA` is added to the operating
system trust store; `Bongo Untrusted Test Root CA` remains outside it so that
certificate rejection and fallback behavior can be tested without corrupting
a certificate:

```sh
sudo ./contrib/testing/local-test-pki.py prepare
sudo ./contrib/testing/local-test-pki.py install
sudo ./contrib/testing/local-test-pki.py status
```

Issue short-lived server certificates from either root with one or more DNS
names and optional IP subject alternative names:

```sh
sudo ./contrib/testing/local-test-pki.py issue \
  --name smtp-valid \
  --dns-name smtp-valid.bongo.test \
  --ip-address 127.0.0.2
sudo ./contrib/testing/local-test-pki.py issue \
  --ca untrusted \
  --name smtp-untrusted \
  --dns-name smtp-untrusted.bongo.test \
  --ip-address 127.0.0.3
```

Private CA keys and issued private keys remain below
`/var/lib/bongo-test-pki` with root-only permissions. Remove the trusted root
after the local release tests:

```sh
sudo ./contrib/testing/local-test-pki.py remove
```

The helper runs Gentoo's `update-ca-certificates`, which rebuilds
`/etc/ssl/certs/ca-certificates.crt` and the hashed certificate links used by
OpenSSL-compatible clients. Bongo's GnuTLS connections load the same system
trust store. Applications with their own NSS database, including many browser
profiles, need separate enrollment and are outside this protocol fixture.

The live user-layout check deliberately retains its clearly named accounts so
later Queue, quota, and protocol matrix rows can reuse them:

```sh
export BONGO_ALLOW_LIVE_USER_TEST=1
export BONGO_TEST_PASSWORD='a-disposable-password-of-at-least-12-characters'
./contrib/testing/store-user-layout-check.sh
```

The Queue-to-Store byte-preservation check uses the retained `stqqueue`
account. It creates a target-999 diagnostic entry, exports the exact
Queue-owned bytes, delivers that entry through Queue's local Store path, and
compares the resulting Store object byte-for-byte:

```sh
./contrib/testing/queue-store-byte-check.sh
```

The script deletes the held Queue entry even on failure. It deliberately
retains the delivered Store object as release evidence. Set
`BONGO_QUEUE_TOOL`, `BONGO_STORE_TOOL`, or `BONGO_TEST_RUN_AS` only when
testing a non-standard installation.

The Queue disk-space check brackets `QDSPC` with filesystem samples and
verifies that the suffixless `queue` configuration's `minimumfreespace`
reserve was subtracted without 32-bit truncation:

```sh
./contrib/testing/queue-disk-space-check.sh
```

The bounded collector flood check seeds separate POP3 and IMAP Cyrus source
accounts with 128-KiB messages, delivers them against a small Store quota, and
then temporarily lowers the Collector per-user pending limit to one. It
verifies unique delivery across Store and Queue, exact quota enforcement, and
that the first over-limit source message remains at Cyrus:

```sh
export BONGO_ALLOW_LIVE_USER_TEST=1
export BONGO_TEST_USER=stqquota
export BONGO_TEST_PASSWORD='a-disposable-password-of-at-least-12-characters'
./contrib/testing/collector-flood-quota-check.py
```

The script restores quota and Collector configuration and removes its source,
Queue, Store, and external-account fixtures. Use
`BONGO_TEST_CLEANUP_ONLY=1` to clean up a previously interrupted run.

The Queue failure-safety check retains one isolated message in an 8 MiB tmpfs
fixture while it first fills that filesystem below the operative reserve and
then overlays the spool with an unreadable directory. It verifies
rejection/defer responses, restores all mounts through traps, and compares the
retained message byte-for-byte after both recoveries:

```sh
./contrib/testing/queue-failure-safety-check.sh
```

It requires passwordless permission for Bongo service start/stop/restart,
`mount`, `umount`, and `stat` on the dedicated test spool. Run it only on a
disposable test installation.

The Store protocol safety check is non-destructive and requires the two
disposable users retained by `store-user-layout-check.sh`:

```sh
export BONGO_TEST_PASSWORD='a-disposable-password-of-at-least-12-characters'
./contrib/testing/store-protocol-safety-check.py
```

The password is read only from the environment and is redacted by the Store's
command logger. The test deliberately attempts `REINDEX`, `REPAIR`, `RESET`,
and `SHUTDOWN` as a normal user; run it only against a build where those
commands require manager privileges.

The live Store quota check uses the retained `stqquota` account. It reads and
restores the account's original limit, removes every fixture document, and
requires explicit destructive-test opt-in:

```sh
export BONGO_ALLOW_LIVE_USER_TEST=1
export BONGO_TEST_PASSWORD='a-disposable-password-of-at-least-12-characters'
./contrib/testing/store-quota-concurrency-check.py
```

The script invokes `sudo -n bongo-admin user quota` only to set and restore the
temporary administrative limit. The password is never passed on a command
line.

The partial Queue quota check creates two held messages and temporarily leaves
space for exactly one of them. It verifies that the first reaches Store, the
second remains byte-identical in Queue after Store returns quota exceeded, and
the retained message is delivered exactly once after the first is deleted:

```sh
export BONGO_ALLOW_LIVE_USER_TEST=1
export BONGO_TEST_PASSWORD='a-disposable-password-of-at-least-12-characters'
./contrib/testing/queue-quota-partial-check.py
```

Every fixture message and Queue entry is removed and the original quota is
restored, including after a failed assertion.

The normal SMTP companion check submits an authenticated message to the full
test mailbox. It verifies that SMTP accepts the durable Queue transaction,
Store receives no partial object, the sender receives exactly the standard
`5.2.2` DSN, and that ordinary SMTP mail is not retained indefinitely:

```sh
export BONGO_ALLOW_LIVE_USER_TEST=1
export BONGO_TEST_PASSWORD='a-disposable-password-of-at-least-12-characters'
./contrib/testing/smtp-quota-dsn-check.py
```

The Collector companion creates a real Queue transaction carrying
`MSG_FLAG_COLLECTED_MESSAGE`. It proves that a full Store keeps the sole
durable copy in local-delivery queue 6, never hands it to the outgoing SMTP
agent, and delivers it exactly once after the quota is released:

```sh
export BONGO_ALLOW_LIVE_USER_TEST=1
export BONGO_TEST_PASSWORD='a-disposable-password-of-at-least-12-characters'
./contrib/testing/collector-quota-retry-check.py
```

Set `BONGO_TEST_TRACE=1` to print bounded per-stage timings. On failure,
fixtures are normally removed and the original quota is restored. For local
diagnosis only, `BONGO_TEST_KEEP_FAILURE=1` preserves the matching Queue entry
while still restoring the quota; remove that entry with `bongo-queuetool
delete` after inspection.

The quota-state companion covers administrative transitions and portable
Store restore semantics. It lowers a limit below current usage, proves that
growth remains blocked, removes the limit, checks the signed 64-bit maximum
and its overflow boundary, then verifies that PAX restore reconstructs exact
logical usage without replacing the target account's administrative limit:

```sh
export BONGO_ALLOW_LIVE_USER_TEST=1
export BONGO_TEST_PASSWORD='a-disposable-password-of-at-least-12-characters'
./contrib/testing/store-quota-state-check.py
```

This test backs up the complete disposable account before modifying it and
restores both the original Store content and quota in its cleanup path.

The Debian source probes and package-build commands used by BLD-14/BLD-15 are
consolidated in `contrib/debian/build-trixie-bundle.sh`; they are not maintained
as duplicate container-only snippets here.

## Cyrus IMAP, POP3, and LMTP

Install `net-mail/cyrus-imapd`, then start the disposable fixture as root:

```sh
sudo ./contrib/testing/cyrus-fixture.py start
```

It creates no files outside `/tmp/bongo-cyrus-fixture` and listens on:

- IMAP: `127.0.0.1:18143`
- POP3: `127.0.0.1:18110`
- LMTP: `127.0.0.1:18024`

The source mailboxes form a multi-account-per-user matrix:

| Bongo owner | Cyrus source account | Protocol | Bongo destination |
| --- | --- | --- | --- |
| `test1` | `test1-pop@cyrus.bongo.test` | POP3 | `INBOX` |
| `test1` | `test1-imap@cyrus.bongo.test` | IMAP | `Cyrus IMAP` |
| `test2` | `test2-pop@cyrus.bongo.test` | POP3 | `INBOX` |
| `test2` | `test2-imap@cyrus.bongo.test` | IMAP | `Cyrus IMAP` |

All source accounts use the test-only password
`BongoCollector-Test-2026`. Insert a complete RFC 5322 message through Cyrus'
real LMTP delivery path:

```sh
sudo ./contrib/testing/cyrus-fixture.py inject message.eml
```

Seed three different messages in each source mailbox and exercise Bongo's real
Collector POP3 and IMAP transport implementation:

```sh
./contrib/testing/cyrus-fixture.py verify-collector \
  --probe ./build/src/agents/collector/collector-remote-transport-probe \
  --count 3
```

The probe lists and fetches every message, checks its fixture marker, deletes
it through the selected protocol, and verifies that every Cyrus source mailbox
is empty. A live end-to-end run creates all four Bongo external-account
records. This proves that accounts, remote UID/UIDL values, retry state and
deletion state remain scoped by account ID even when one Bongo user owns
multiple sources. All four use `after_import`, so Cyrus deletion happens only
after the Bongo Queue has durably accepted and committed the complete message.
From that point the normal scanner, rules, quota, and Store delivery pipeline
owns it.

The fixture can also seed deterministic scanner and quota cases. All ports
remain loopback-only and the flood is deliberately bounded:

```sh
sudo ./contrib/testing/cyrus-fixture.py seed --profile gtube --count 1
sudo ./contrib/testing/cyrus-fixture.py seed --profile eicar --count 1
sudo ./contrib/testing/cyrus-fixture.py seed --profile flood --count 32 \
  --message-size 131072
sudo ./contrib/testing/cyrus-fixture.py seed-suite
```

`gtube` contains SpamAssassin's standard GTUBE string. `eicar` creates the
harmless standard EICAR attachment at runtime; the complete signature is kept
out of the Git checkout to avoid host antivirus false alarms. `seed-suite`
places three normal messages, one GTUBE message, one EICAR message, and 32
128-KiB flood messages in every source mailbox (148 messages total). Set a
small quota on disposable Bongo users before collection, then restore it after
the test. The test passes only when clean messages are imported, scanner
policy is applied, quota cannot be exceeded, and a message rejected before a
durable import remains retrievable from Cyrus.

The same LMTP listener is the forwarding target for the exact transport-domain
mapping below. This accepts `*@cyrus.bongo.test` without making the test domain
a local Bongo domain:

```json
"lmtp_transports": ["cyrus.bongo.test=127.0.0.1:18024"]
```

Cyrus `lmtpd` is pre-authorized only on this loopback-only fixture listener.
That matches a trusted local MTA-to-store LMTP hop and must not be copied to a
network-exposed Cyrus listener.

The generated short-lived test CA at
`/tmp/bongo-cyrus-fixture/tls/ca.crt` is the fixture trust anchor. Set
`BONGO_COLLECTOR_CAINFO` to that path for the Collector process during this
test; normal installations continue to use the operating-system trust store.
The packaged `bongo.service` uses `PrivateTmp=true`, so a live systemd test
must make the fixture visible inside that service namespace. A runtime-only
drop-in can bind precisely this fixture read-only:

```ini
[Service]
BindReadOnlyPaths=/tmp/bongo-cyrus-fixture
```

Install it with `systemctl edit --runtime bongo.service`, restart Bongo, and
set the Collector `ca_file` to the path above. Do not weaken certificate or
host-name verification for the test.

After a live collection cycle, show the source-mailbox counts with:

```sh
./contrib/testing/cyrus-fixture.py mailbox-status
```

Stop or remove all fixture state with:

```sh
sudo ./contrib/testing/cyrus-fixture.py stop
sudo ./contrib/testing/cyrus-fixture.py reset
```

## Internal SMTP relay policy

The live port-26 check changes rate limits and restarts Bongo several times.
It therefore requires an explicit opt-in and must only be run against a
disposable test installation:

```sh
export BONGO_ALLOW_LIVE_SMTP_TEST=1
./contrib/testing/smtp-internal-relay-check.py
```

The default test topology binds the allowed client to `172.16.11.190` and the
denied client to `127.0.0.1`, both connecting to
`172.16.11.190:26`. Override `BONGO_TEST_INTERNAL_HOST`,
`BONGO_TEST_ALLOWED_SOURCE`, or `BONGO_TEST_DENIED_SOURCE` when the fixture
uses different addresses. The script verifies exact protocol responses,
temporarily tests one connection, one recipient, 64 bytes, and one message
per rate window, and restores the original SMTP document even after failure.
After every service restart it allows a two-second agent startup grace period
and then requires two successful SMTP readiness sessions. Override the grace
period with `BONGO_TEST_STARTUP_GRACE` if slower test hardware needs it. Its
DATA transactions are deliberately rejected before Queue commit.

The companion SMTP-05 check temporarily maps the allowed source IP to the
device name `matrix` and points remote delivery at unreachable loopback
`127.0.0.2`. This safely leaves each accepted `.invalid` message available
for `bongo-queuetool show`, where the script verifies the actual Queue
envelope rather than log text:

```sh
export BONGO_ALLOW_LIVE_SMTP_TEST=1
./contrib/testing/smtp-internal-normalization-check.py
```

It covers `root@localhost`, another local user, case-insensitive
`localhost.localdomain`, single and nested hosted subdomains converted to
plus-addresses, a correct hosted-domain sender that remains unchanged, a
lookalike domain-boundary
attack, an unrelated domain that is canonicalized, and the null reverse path.
Focused native tests cover explicit IP mapping, DNS suffix boundaries,
forward-confirmed reverse DNS, invalid host labels, truncation, and the rule
that either authenticated submission or a trusted internal connection may
relay to a remote recipient. A source outside
`internal_relay_networks` remains rejected before the SMTP greeting.

## Authenticated external SMTP provider

Xeams DevNullSMTP is useful as a deliberately simple relay capture, but it
cannot exercise an external user's SMTP authentication and TLS settings.
`smtp4dev-fixture.py` starts two independent smtp4dev instances for those
tests:

- STARTTLS SMTP: `127.0.0.1:12587`, API: `127.0.0.1:15080`
- implicit TLS SMTP: `127.0.0.1:12465`, API: `127.0.0.1:15081`
- username: `provider`
- disposable password: `BongoProvider-Test-2026`
- trust anchor: `/tmp/bongo-smtp4dev-fixture/tls/ca.crt`

Both SMTP listeners and both HTTP APIs bind only to loopback. AUTH is not
offered before STARTTLS, only PLAIN and LOGIN are enabled after encryption,
and smtp4dev's permissive `SmtpAllowAnyCredentials` development default is
explicitly disabled.

The fixture can use an existing executable through `SMTP4DEV_BIN`. The
following pinned upstream CI build was used for the 0.7 local test:

```sh
curl -fL -o /tmp/Rnwood.Smtp4dev-linux-x64-3.16.0-ci20260724100_pr2100.zip \
  https://github.com/rnwood/smtp4dev/releases/download/3.16.0-ci20260724100_pr2100/Rnwood.Smtp4dev-linux-x64-3.16.0-ci20260724100_pr2100.zip
./contrib/testing/smtp4dev-fixture.py prepare \
  --archive /tmp/Rnwood.Smtp4dev-linux-x64-3.16.0-ci20260724100_pr2100.zip
```

The helper requires the pinned SHA-256
`4bcff7d9ecbb62d3abe44888ba38502674b9a634c6b87453e43f1af272bd4249`.
An archive with another name is accepted only with an explicit `--sha256`;
every member is checked for path traversal and symbolic links before
extraction. The downloaded binary is not redistributed by Bongo.

Start and validate the two instances:

```sh
./contrib/testing/smtp4dev-fixture.py start
./contrib/testing/smtp4dev-fixture.py verify
```

The verification performs valid and invalid authentication over both TLS
modes, submits a unique local capture through each listener, checks its
summary and raw RFC 5322 source through `/api/messages`, then deletes only
those probe messages. Later relay and external-identity tests can query the
same supported API to verify the exact envelope, headers, MIME body, DKIM
signature, and authenticated provider account.

Remove captured messages without changing the process configuration, or stop
and remove the entire disposable fixture:

```sh
./contrib/testing/smtp4dev-fixture.py clear
./contrib/testing/smtp4dev-fixture.py stop
./contrib/testing/smtp4dev-fixture.py reset
```

## Outbound SMTP capture

Use `net-mail/xeams-devnullsmtp-bin` from the Bongo Gentoo overlay:

```sh
xeams-devnullsmtp -p 2526 -d bongo.test -s /tmp/bongo-devnull-mail
```

Configure `127.0.0.1:2526` as Bongo's relay host before testing any non-local
recipient.  Xeams DevNullSMTP has no listen-address option, so isolate it with a
firewall or network namespace; do not expose it on a production network.

## HAProxy and PROXY v2

`haproxy-bongo-test.cfg` exposes loopback-only high ports and forwards every
connection to the corresponding normal Bongo listener with a PROXY v2 header.
Before starting it, temporarily enable `proxy_protocol_enabled` and set
`proxy_protocol_networks` to `["127.0.0.1/32"]` in the `smtp`, `imap`, `pop3`,
and `sieve` documents. Never trust an unbounded network for PROXY headers.

Validate and run the fixture in the foreground:

```sh
haproxy -c -f contrib/testing/haproxy-bongo-test.cfg
haproxy -db -f contrib/testing/haproxy-bongo-test.cfg
```

The test listeners are SMTP `11025`, submission `11587`, submissions `11465`,
IMAP `11143`, IMAPS `11993`, POP3 `11110`, POP3S `11995`, and ManageSieve
`14190`. Exercise real protocol greetings, capabilities, authentication, and
TLS handshakes through these ports, then restore the original Bongo documents.