DNS Blocklist Monitoring
If your server's IP lands on a public spam or abuse blocklist (DNSBL), your email stops getting delivered and some networks start dropping your traffic — usually without any error you'd notice. Blocklist monitoring checks your true origin IP against dozens of well-known lists and alerts you the moment you're listed.
How it works
On each run the checker resolves your origin IP — the real server address, not the CDN or proxy edge in front of it — and queries a curated set of public DNSBLs (spam, abuse, and policy lists). For each list it records listed / not listed and, where provided, the reason and the delisting URL.
Checking the origin matters: a blocklisting is about the machine actually sending mail or serving traffic, so testing the CDN edge would miss the problem entirely. Checks run on a regular cadence.
What triggers an alert
- Your origin IP is newly listed on one or more monitored blocklists.
- A listing persists across runs (so you're reminded until it's resolved).
The monitor clears automatically once every list reports your IP as delisted again.
Setting it up
- Add monitor and choose DNS Blocklist.
- Enter your origin IP (or the hostname to resolve to it). If your site sits behind a CDN, use the address of the box that actually sends mail / serves origin traffic.
- Review the blocklists to watch (a sensible default set is preselected).
- Set the check interval.
- Attach notifications — route to whoever owns deliverability.
When you're listed, use the delisting link the monitor surfaces to request removal, then fix the root cause (compromised account, misconfigured mail server, or shared-IP reputation) before it recurs.
Related
- DNS · Domains · Port Scan
- Notifications
- Marketing: DNS blocklist monitoring feature