MXToolbox

@MXToolbox check if our domain example.com is on any blacklists and show me the DMARC policy

Blacklist check for example.com shows clean across 87 monitored lists — no listings found on Spamhaus, Barracuda, or SORBS. DMARC record retrieved: 'v=DMARC1; p=quarantine; pct=100; rua=mailto:dmarc@example.com' — policy is set to quarantine suspicious messages with aggregate reports enabled. This illustrative example shows how the MCP combines multiple DNS security checks in a single query.

This example demonstrates read-heavy lookups combining blacklist monitoring with email authentication policy checks. Requires API key with sufficient quota — blacklist checks consume multiple API calls per domain (one per list checked). Results reflect point-in-time status; blacklist inclusion can change hourly.

@MXToolbox verify DKIM and SPF records for newdomain.io before we start sending customer emails

DKIM lookup for newdomain.io returns no valid records found — you'll need to publish a DKIM selector before sending authenticated mail. SPF record retrieved: 'v=spf1 include:_spf.google.com ~all' — configured for Google Workspace with soft fail policy. This illustrative response shows pre-send validation catching missing authentication that would hurt deliverability.

This example showcases proactive email authentication verification before launching campaigns. Catches configuration gaps early — missing DKIM or weak SPF policies directly impact inbox placement rates. Each DNS lookup counts against your MXToolbox API quota; monitor usage via the Check Usage tool.

@MXToolbox run a full email security audit on clientdomain.com and summarize what needs fixing

Audit complete for clientdomain.com. Critical findings: (1) DMARC policy set to 'p=none' — monitoring only, not enforcing. (2) MTA-STS record missing — no transport security policy published. (3) BIMI record not found — brand logo won't display in supported email clients. Positive: DKIM properly configured, blacklist status clean. This illustrative summary shows the AI synthesizing multiple MXToolbox lookups into prioritized remediation steps.

This example pairs the MCP's DNS lookup tools with AI reasoning to deliver actionable security posture analysis. Executes 5-7 API calls in sequence (DMARC, DKIM, SPF, MTA-STS, BIMI, blacklist checks). Useful for onboarding new domains or quarterly audits — but watch quota limits on bulk assessments.

When MXToolbox saves your outbound email reputation

A 6-person SaaS startup notices their onboarding emails landing in spam. The support lead needs to audit SPF, DKIM, and DMARC records without waiting on engineering. MXToolbox is the right call here: the Lookup DKIM Record, Lookup DMARC Record, and Lookup Blacklist tools let non-technical teammates diagnose misconfiguration in minutes. The Check Usage tool keeps you honest about API limits if you're running daily checks. This MCP stops being useful once you need continuous monitoring or alerting—at that scale, you want a dedicated email-ops platform. For one-off audits or quarterly hygiene checks, MXToolbox gives your team the DNS literacy to fix deliverability without opening a DevOps ticket.

Blacklist checks during a phishing scare

A 12-person agency gets a client complaint that their domain is flagged as suspicious. The account manager needs to confirm whether the domain or IP is actually blacklisted before escalating to IT. The Lookup Blacklist tool checks common blocklists in one call, and the Lookup DNS Records tool surfaces any hijacked subdomains. MXToolbox works well here because the scenario is reactive and infrequent—you're not running these checks hourly. If your team handles security incidents weekly or needs automated threat feeds, this MCP is too manual. For ad-hoc "are we compromised" questions during a fire drill, MXToolbox gives non-engineers the forensic data to triage fast.

Auditing a new domain before go-live

A 4-person product team is launching a new marketing site on a fresh domain. Before flipping DNS, they need to verify HTTP connectivity, MTA-STS policy, and BIMI branding records. The HTTP Lookup, Lookup MTA-STS Record, and Lookup BIMI Record tools let the PM run a pre-flight checklist without SSH access or command-line tools. MXToolbox is ideal for this one-time validation—13 tools cover the full DNS and email stack. It stops being the right choice if you're launching domains monthly and need CI/CD integration. For teams that ship a new domain twice a year and want a human-readable audit trail, MXToolbox turns launch-day paranoia into a 10-minute checklist.