Mail server address is listed on a blocklist

Why it matters

When the check passes, your report says: “Mail server addresses are clear on every list we checked”.

When this check fails it removes 40 points from your Email reputation score, before the status, confidence and repeat multipliers are applied. Email reputation carries a weight of 5 in the overall score.

It shares the email-reputation.blocklists family ceiling of 80 points: however many findings that family produces, together they cannot remove more than that from Email reputation. One underlying problem showing up in several places is still one problem.

Severity

critical

Default confidence

confirmed

Status when triggered

fail

Deduction

40 points

Family cap

email-reputation.blocklists · 80

Category

Email reputation

Module

Email blocklists

Fix owned by

user

In the ruleset since

2026.09

How the whole score is calculated

1. Find the cause first. The usual four are: a compromised mailbox or web script sending spam; an open relay; a mailing list sending to addresses that never opted in; and a shared address whose neighbour is the actual sender.

2. Check your mail queue and outbound logs for volume you did not send. On a shared or cloud host, check whether the address is yours alone.

3. Fix what you find — rotate the compromised credentials, patch or remove the script, close the relay.

4. Then request removal at ‹delisting url›. Most lists remove within hours once the cause has stopped.

5. Confirm the supporting configuration is right so it does not recur: reverse DNS for the address, an SPF record that does not authorise more than it should, and DMARC at enforcement.

How to confirm it worked

• Re-run this check after requesting removal; the listing should be gone.

• Send a test message to a mailbox at a large provider and confirm it reaches the inbox.

A named slot like ‹domain› — and the braces left in the configuration below — is filled in with your own values when this rule appears on a report.

Run the check that produces this finding, on its own, against any domain.

Open the email blocklists checker

• Listed on a source we show but do not score
• Which blocklists we check, and which we do not
• Domain is listed on a domain reputation blocklist
• A blocklist did not answer, so it is not counted as clean