IP not blacklisted
International organisations maintain blacklists of IP addresses known for sending spam or distributing malware. This check verifies whether …
Analyse my site for freeUnderstanding "IP not blacklisted"
DNS blacklists (DNSBL — DNS-based Blackhole Lists), such as Spamhaus or SpamCop, list IP addresses identified as sources of spam, malware, or other abusive activity. These lists are queried in real time by many mail servers and firewalls worldwide to decide whether to block traffic from a given IP.
If your server's IP address appears on one of these lists — often due to a past incident (a compromised account used for spam, shared hosting with a malicious neighbour, a poorly secured server exploited without your knowledge) — your own legitimate emails can be automatically rejected or marked as spam by a large share of recipients.
How TheSiteFuse checks "IP not blacklisted"
TheSiteFuse resolves the domain's IP address, then queries 3 recognised DNS blacklists (zen.spamhaus.org, bl.spamcop.net, dnsbl.sorbs.net) following the standard DNSBL protocol (a query on the reversed IP suffixed with the list's name). A response starting with 127. indicates a listed IP — except for 127.255.x.x responses, which are Spamhaus-internal error or policy codes (e.g. "too many queries") and don't mean the IP is actually blacklisted. Any list where the IP is confirmed listed triggers an error.
Why "IP not blacklisted" matters
- Severely degraded email deliverability — an IP on a major blacklist like Spamhaus can have its emails rejected outright (not even landing in spam) by a significant share of business mail servers worldwide.
- Impact on any email-dependent activity — order confirmations, invoices, password resets, transactional notifications: every outgoing email from that IP is affected, not just marketing campaigns.
- Shared hosting — a risk outside your direct control — on a shared server, another customer's malicious activity on the same IP can get the address blacklisted without you having done anything wrong yourself.
Fix "IP not blacklisted" step by step
Step 1 — Confirm and understand the listing
Check the relevant organisation's lookup page directly (e.g. check.spamhaus.org) to learn the exact reason for the blacklisting — essential information before requesting removal.
Step 2 — Fix the root cause
Depending on the identified reason: secure a compromised account (change every password, scan for malware), fix an open-relay mail server misconfiguration, or switch hosts if the issue stems from a recurring malicious shared-hosting neighbour.
Step 3 — Request delisting
Every blacklist offers a removal request form, generally free, once the cause has been fixed. Processing time ranges from a few minutes (SpamCop) to several days (some stricter lists).
Prevention: regularly monitor your IP reputation with tools like MXToolbox, and consider a reputable third-party SMTP relay service (SendGrid, Amazon SES…) that actively manages its IP reputation on your behalf for critical transactional sending.
Reference resource
To deepen your understanding of the technical concepts behind this check, see the dedicated Wikipedia article.
Wikipedia — IP not blacklistedDoes your site pass this check?
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