How to Use eWall SMTP Proxy Free for Secure Email Relay

Troubleshooting eWall SMTP Proxy Free: Common Issues & Fixes

1. Service won’t start

• Symptom: Proxy process fails to start or immediately exits.
• Fixes:
  1. Check logs (default log file or system journal) for error lines.
  2. Verify binary permissions and executable bit.
  3. Ensure required dependencies/libraries are installed.
  4. Run the process manually in a terminal to capture stderr.

2. Cannot connect from clients (SMTP connection refused or timed out)

• Symptom: Telnet/mail client reports connection refused or timeout on port ⁄₅₈₇.
• Fixes:
  1. Confirm proxy is listening: netstat -tlnp or ss -tlnp.
  2. Check firewall (iptables/nftables/ufw) and cloud security groups; allow the SMTP port.
  3. Ensure SELinux/AppArmor rules aren’t blocking the binary.
  4. Verify the service is bound to the expected IP (0.0.0.0 vs localhost).

3. Authentication failures with upstream SMTP server

• Symptom: Relay attempts fail with 5xx/4xx auth errors.
• Fixes:
  1. Check stored credentials for typos and correct encoding.
  2. Confirm auth method supported by upstream (LOGIN/PLAIN/CRAM-MD5).
  3. Ensure TLS/SSL settings match upstream requirements (STARTTLS vs SMTPS).
  4. Inspect logs for SASL errors and test credentials directly with openssl s_client or swaks.

4. Emails queued and not relayed

• Symptom: Messages remain in local queue.
• Fixes:
  1. Inspect queue status via the proxy’s queue command or log messages.
  2. Check DNS/MX resolution for destination domains.
  3. Verify upstream connectivity and authentication.
  4. Look for rate limiting or temporary upstream errors (4xx responses); implement retry/backoff.

5. SSL/TLS handshake failures

• Symptom: TLS negotiation errors, certificate verification failures.
• Fixes:
  1. Confirm certificate files exist and are readable by the service.
  2. Verify certificate chain is complete and CA is trusted on the system.
  3. Check cipher suites and protocol versions; enable compatible TLS versions.
  4. Test with openssl s_client -starttls smtp to observe handshake details.

6. High latency or dropped connections

• Symptom: Slow mail delivery, intermittent disconnects.
• Fixes:
  1. Monitor network performance (ping, traceroute) to upstream server.
  2. Check system resource usage (CPU, memory, file descriptors).
  3. Increase connection/timeouts and tune keepalive settings.
  4. Inspect for throttling by upstream provider (per-IP limits).

7. Logging is sparse or unhelpful

• Symptom: Logs lack detail needed for debugging.
• Fixes:
  1. Increase log verbosity in configuration (debug/trace).
  2. Enable structured/log rotation settings to preserve context.
  3. Capture a repro with debug enabled and examine timestamps and SMTP responses.

8. Spam/blacklisting issues after relay

• Symptom: Delivered mail marked spam or IP listed on RBLs.
• Fixes:
  1. Check PTR, SPF, DKIM, and DMARC records for your sending domain/IP.
  2. Ensure proper HELO/EHLO name and matching reverse DNS.
  3. Request delisting from RBLs after resolving root cause.
  4. Implement rate limits and outbound content checks.

Quick diagnostic checklist

1. Check service status and listening ports.
2. Review recent logs (errors and auth attempts).
3. Validate DNS and upstream connectivity.
4. Confirm TLS and credential settings.
5. Verify firewall/SELinux permissions and resource usage.

If you want, tell me the exact error lines from your logs and I’ll give targeted fixes.