Overview
Founded in 2003 and headquartered in the United States, MXToolbox is a globally recognized online email and DNS diagnostic platform. It offers 200+ free online diagnostic tools covering DNS lookup, blacklist checking, SMTP testing, email path tracing, and domain health monitoring.
MXToolbox is the go-to toolbox for email administrators, ISP operations teams, and domain managers. Whether troubleshooting email delivery failures, checking if a domain is blacklisted, or verifying DNS configuration correctness, MXToolbox delivers fast, free diagnostic results.
Key Strengths
- 200+ Free Online Tools: Covers DNS lookups (A/AAAA/MX/TXT/CNAME/NS), blacklist checks (100+ data sources), SMTP testing, email header analysis, port scanning, and more — no registration required.
- Comprehensive Blacklist Check: One-click lookup to check if sending IPs or domains are listed on 100+ major blacklist databases including Spamhaus, Barracuda, SORBS, and SpamCop, with listing details and removal guidance.
- SMTP Server Diagnostics: Tests SMTP connectivity, STARTTLS encryption support, and mail relay configuration to quickly identify email sending failures.
- Domain Health Monitoring: Schedule recurring checks to monitor DNS record status, blacklist status, and mail server availability — alerts via email or Webhook on anomalies.
Product Ecosystem
- DNS Lookup Tools: Supports A, AAAA, MX, TXT, CNAME, NS, SOA, and other record types, with DNSSEC validation and DNS propagation delay detection.
- Blacklist Check: Enter an IP address or domain to automatically query 100+ blacklist databases, returning results and response times for each source.
- SMTP Diagnostics: Simulates the email sending process, testing SMTP handshake with the target MX server, verifying SPF records, reverse DNS, and STARTTLS support.
- Email Header Analyzer: Paste raw email headers for automatic parsing and visualization — see the complete delivery path, MTA hops, latency, and authentication status.
- Domain Monitor: Create monitoring tasks for scheduled checks on DNS record changes, blacklist status changes, and server port availability, with customizable intervals and alert thresholds.
Limitations
- Free Tool Limitations: Free tools are suitable for one-time diagnostics but cannot replace professional monitoring services for production environments requiring continuous oversight.
- Advanced Monitoring Requires Payment: Domain monitoring, scheduled checks, and historical data queries require an MXToolbox Pro subscription.
- No Unified API: Most tools are available via web interface only — no comprehensive REST API for deep integration into automated operations workflows.
- English-Only Interface: Limited localization beyond English, which may affect non-English-speaking users when using advanced tools.
Use Cases
- Email Delivery Troubleshooting (★★★★★): Quickly identify root causes of email failures or delays using SMTP testing, blacklist checks, and email header analysis.
- DNS Configuration Validation (★★★★★): After domain migration or new configuration deployment, verify all DNS records with one click.
- Sending Domain Health Monitoring (★★★★): Set up recurring monitoring tasks to track DNS and blacklist status changes for sending domains.
- Daily Ops Toolbox (★★★★): 200+ free tools across DNS, email, and network domains — essential for network administrators and operations engineers.
Pricing
| Plan | Features | Price | Key Capabilities |
|---|---|---|---|
| Free Tools | 200+ tools | $0 | One-time diagnostics, DNS lookups, blacklist checks |
| Pro | Monitoring + Alerts | Contact Sales | Domain monitoring, scheduled checks, historical data, email alerts |
| Enterprise | Bulk Monitoring | Contact Sales | Multi-domain batch monitoring, API access, dedicated support |
FAQ
Do I need to register to use MXToolbox? Most free tools are accessible without registration. Creating monitoring tasks and subscribing to Pro require an account. See Email Service Provider Comparison.
What do I do after a blacklist check result? MXToolbox provides removal guidance links for each blacklist. Typically, you need to visit the listing blacklist's website and follow their delisting process. See Email Deliverability Optimization.
Can I send emails with MXToolbox? No. MXToolbox is a diagnostic and analysis tool and cannot send emails. Use an SMTP relay or email API service for sending. See SMTP Configuration Guide.
What's the difference between MXToolbox and GlockApps? MXToolbox focuses on DNS and mail server diagnostics (DNS lookups, SMTP testing, blacklist checks), while GlockApps focuses on email content inbox placement testing and DMARC compliance analysis. They complement each other for comprehensive email operations.