README

# Athexa APEX SMTP Relay

Windows SMTP relay for Oracle APEX (Delphi 12, Indy) with durable disk spool, retry policy, and restricted inbound access.

What Is New In UI

1. Static DFM-based UI (no runtime component generation).
2. Tabs: Dashboard, Config, Log.
3. Dashboard includes:
   • Queue summary block,
   • Actions block,
   • Relay status block,
   • Messages per hour (last 24h) chart,
   • pie charts for inbound/outbound distribution and problematic percentage.
4. Config tab includes grouped settings for:
   • Inbound,
   • Inbound auth,
   • Outbound,
   • Outbound auth,
   • Queue,
   • UI config,
   • Retry policy.
5. Log tab contains live in-memory log memo.
6. Multi-language captions/hints: English, Russian, Indonesian.

Highlights

1. Inbound SMTP listener for APEX only (AllowedClientIP).
2. Inbound SMTP auth support: CRAM-MD5, LOGIN, PLAIN.
3. Inbound auth requirement logic:
   • if RequireAuthCredentials = false, anonymous sending is allowed;
   • if RequireAuthCredentials = true and inbound credentials are filled, MAIL FROM requires successful AUTH;
   • if inbound username/password are empty, relay allows both authenticated and anonymous flow regardless of checkbox.
4. Outbound delivery to smarthost with PLAIN, STARTTLS, or SSL_IMPLICIT.
5. Durable queue (new, inflight, deferred, dead, tmp) with crash recovery.
6. Retry policy with exponential backoff + jitter.
7. Flush Now forces deferred items to due now and wakes sender workers.
8. Dead-letter purge from UI.
9. In-memory ring log (no file logs).
10. Optional detailed SMTP tracing (C:, S:, C-DATA:, EVT:) via UI checkbox.
11. Credentials are encrypted and stored in INI:
    • [Inbound] AuthUser/AuthPassword,
    • [Outbound] AuthUser/AuthPassword.
12. Runtime state persistence: listener/senders auto-start after restart if they were running before shutdown.
13. Reset to defaults keeps outbound SMTP credentials intact.
14. Any setting change is saved automatically (no explicit Save button).
15. If listener/senders are running, they are restarted automatically after config change.

Build

Open MailRelay.dproj in RAD Studio 12 and build Win32 Debug (or Release).

Runtime Notes

1. Keep OpenSSL DLLs near executable for TLS modes in Indy.
2. Default queue path is ./spool.
3. Active config path is logged as Using INI: <path>.
4. Queue and dashboard charts are based on queue snapshot metadata.

User Scenarios

1) Basic Oracle APEX Relay (No Inbound AUTH Required)

Use when Oracle APEX is in trusted local network.

1. Open Config tab.
2. In Inbound config, set Bind IP, Bind Port, Allowed Client IP (comma-separated list is supported).
3. In Inbound auth config, keep username/password empty and uncheck Require auth credentials.
4. In Outbound config, set smarthost host/port/TLS/workers.
5. In Outbound auth credentials, set smarthost login/password if required by provider.
6. Changes are saved automatically after edit.
7. Go to Dashboard, click Start Listener, then Start Senders.

2) Strict Inbound AUTH Required

Use when inbound clients must always authenticate.

1. Open Config tab -> Inbound auth config.
2. Fill inbound Username and Password.
3. Enable Require auth credentials.
4. Changes are saved automatically after edit.
5. Restart listener from Dashboard (Stop Listener -> Start Listener).

Expected behavior:

• MAIL FROM is rejected with auth-required response until AUTH succeeds.

3) Compatibility Mode For Mixed Clients

Use when some clients authenticate and some do not.

1. Keep inbound username/password empty.
2. Require auth credentials may be on or off.
3. Changes are saved automatically after edit.

Expected behavior:

• relay accepts both authenticated and anonymous sessions.

4) Smarthost Credential Rotation Without Downtime

1. Open Config tab -> Outbound auth credentials.
2. Update SMTP username/password.
3. Changes are saved automatically after edit.
4. If senders are running, click Flush Now to accelerate processing.

5) Recover Deferred Queue Immediately

Use after temporary smarthost outage.

1. Ensure senders are running.
2. Click Flush Now in Dashboard.
3. Watch queue counters and charts.

Expected behavior:

• deferred items are marked due-now and reattempted.

6) Clean Up Dead-Letters

1. Click Purge Dead-letters in Dashboard.
2. Confirm action.
3. Verify dead count drops.

7) Safe Reset Of Settings

1. Click Reset to defaults in Config.
2. Confirm action.

Expected behavior:

• most config values return to defaults,
• outbound credentials remain preserved.

8) Capacity Tuning For High Volume

1. Increase Queue MaxQueueItems and Queue MaxQueueBytesMB.
2. Tune retry (MaxAttempts, BaseDelaySec, MaxDelaySec, JitterPct).
3. Increase Workers if smarthost allows parallel sends.
4. Changes are saved automatically; monitor Messages per hour chart.

9) Observability / Troubleshooting Session

1. Enable Enable detail logging.
2. Reproduce issue.
3. Open Log tab and inspect SMTP dialog lines.
4. Disable detail logging after diagnostics to reduce noise.

10) Planned Restart With State Restore

1. Keep listener/senders running.
2. Close application normally.
3. Start application again.

Expected behavior:

• relay restores previous runtime state (ListenerStarted/SendersStarted).

Troubleshooting

1. If inbound AUTH fails unexpectedly, verify inbound username/password and RequireAuthCredentials.
2. If outbound send fails with SMTP 535, re-save outbound credentials and verify:
   • smarthost host/port/TLS,
   • provider account policy,
   • active INI path from Using INI: ....
3. If dashboard looks stale, verify StatsRefreshMs and sender/listener status.
4. If queue growth is too fast, increase queue limits or reduce upstream flow.

License

See LICENSE.md.