Are all blocklists reputation-based?

Not all blocklists work the same way. Some track your behavior over time. Others will list you the moment a technical setting is wrong, regardless of whether you've ever sent a single spam message. Knowing the difference matters a lot when you're trying to figure out why you're listed and what to do about it.

A blocklist (also called a DNSBL, which stands for DNS-based Blocklist) is a published list of IP addresses or domains that receiving mail servers use to decide whether to accept or reject incoming email. Think of them as the no-entry lists that guard the door before your email even reaches the inbox.

Here's how the main types break down:

• Evidence-based lists track direct proof of spam activity. Spamhaus is the biggest example. If your IP or domain hits a spam trap (a deactivated address reactivated to catch senders with bad list hygiene), or gets reported for abuse, you land on the list. The listing is tied to a specific incident.
• Policy-based lists list IPs for technical violations, not spam behavior. Missing reverse DNS (rDNS), running an open relay, or sending from a dynamic residential IP can all trigger a listing here, even if you've never sent a questionable email in your life.
• Reputation-scoring lists aggregate signals from many sources into a trust score and list senders who fall below a threshold. These are closer to the "reputation-based" model most people assume all blocklists follow.
• Spam trap network lists focus specifically on senders who repeatedly hit their network of trap addresses. These are a strong signal of poor list hygiene rather than intentional spam.

Why does this matter in practice? Because the fix depends entirely on the type of listing. An evidence-based listing from Spamhaus requires you to investigate what happened, clean up the root cause, and submit a delisting request with context. A policy-based listing just needs a technical fix, like adding rDNS to your sending IP. Treating them the same way wastes time and can make things worse.

If you're not sure which list you're on or why, our free Blocklist Checker will show you where your domain or IP is flagged right now. And if the result is confusing, the SOS hotline is there for exactly that situation.