Mail Server Security Check — IP & Domain Threat Brief

Complete mail hardening includes TLS configuration, authentication records, rate limits, and monitoring. Blocklist and reputation signals answer whether the internet currently distrusts your IP or domain — often the first symptom of compromise or misconfiguration users notice through bounce messages.

This check does not replace vulnerability scanning or penetration testing. It complements deliverability and auth record tools with threat-oriented context.

Paste egress IPv4 from NDR bounce messages or provider dashboards. IP brief fraudScore and Spamhaus results explain why remote MTAs reject mail. zen SBL listing often indicates compromised account spam or open relay before internal IDS alerts.

Remediate compromise, close relay misconfiguration, then delist through spamhaus-lookup guidance before resuming volume.

Domain brief phishing riskScore flags suspicious hostname patterns on mail-related subdomains. dnsbl listing on sending domain labels affects URI reputation in some filters. emailAuth confirms whether SPF and DMARC publish at all — gaps increase spoofing risk for your brand.

Use email-dns-health-check for structured multi-record mail DNS audit beyond threat brief booleans.

When your mail domain resolves to shared hosting IPv4, ipThreat shows whether that IP carries malware DNSBL hits from co-tenant abuse. Dedicated mail IPs should show clean ipThreat — unexpected hits warrant provider escalation.

CDN and front-door IPs may not reflect actual SMTP submission paths — test known relay IPs directly.

email-deliverability-checker validates MX reachability, SPF syntax, DKIM selectors, and DMARC policy strings. mail-server-security-check adds threat and blocklist context on the same domain or IP from threat-intel merge.

Run both during pre-launch mail infrastructure audits — auth correctness plus external reputation.

Identical threat-intel backend and JSON shape. mail-server-security-check emphasizes MX, relay, and smarthost administrator vocabulary; threat-intelligence-lookup targets general SOC indicator enrichment.

Automation uses action threat-intel with query, ip, or domain parameters regardless of landing page slug.

When sudden global rejection occurs, paste outbound IP here first for Spamhaus and fraudScore snapshot. Parallel run email-deliverability-checker on sending domain for auth breakage. Archive JSON with queriedAt for provider tickets.

Recheck hourly during active delisting — status changes as zones propagate.

GET /ip-tools/api/extended?action=threat-intel&query=mail.example.com or query=203.0.113.25. Server-side extended API — not browser-local. Parse type, summary, emailAuth, spamhaus, reputation, phishing, dnsbl.

Integrate with monitoring scripts that alert when fraudScore or Spamhaus listed flips true on production egress IPs.

Check mail infrastructure you operate or indicators from authorized abuse investigation. Probing third-party mail servers without legitimate cause may violate provider terms.

Heuristic and blocklist signals require human judgment before blocking legitimate transactional mail.