How do I set up automated blocklist monitoring?

Regular blocklist monitoring catches problems before they cause widespread delivery failures. Several approaches exist, from free manual checks to enterprise monitoring solutions.

Free monitoring tools:

• MXToolbox - mxtoolbox.com/blacklists - checks 100+ lists, free monitoring for 1 domain
• DNSBL.info - dnsbl.info - checks 36 active lists
• MultiRBL - multirbl.valli.org - comprehensive free checking

Commercial monitoring services:

• Validity Everest - Enterprise monitoring with alerts and remediation guidance
• 250ok (now Validity) - Integrated into Validity platform
• GlockApps - Affordable option with blocklist monitoring included
• Postmark - Includes monitoring for their customers

What to monitor:

• All sending IPs (including shared ESP IPs if you can identify them)
• Your sending domains
• Any domains appearing in your email content (tracking domains, landing pages)

Monitoring best practices:

• Check at least daily for high-volume senders
• Set up email alerts for new listings
• Prioritize high-impact lists in your response
• Keep records of listings and resolutions for patterns
• Include monitoring in your deliverability dashboard

DIY monitoring script approach:

• Use dig/nslookup to query blocklist zones directly
• Automate with cron jobs or scheduled tasks
• Alert when queries return positive (listed) results

Blocklist monitoring is like having a radio tuned to harbor warnings. You want to know you've been flagged before your next shipment gets stranded at port.