IPBulucu.orgNetwork & DNS Tools
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DNSBL Results & Provider Availability

IP Blacklist & Spam Reputation Check

Query SpamCop and DroneBL, with official lookup links for Spamhaus and Barracuda.

Provider failures and unconfigured access are unknown, never clean. Absence from checked lists does not establish safety or deliverability.

For delivery issues, use the outbound mail IPv4, which may differ from your website. Which IP and error code?

Which IP should I check for email spam?

Use the actual outbound mail server IPv4 from your mail provider or the receiving server's trusted message headers. A website A record or MX record may point elsewhere.

550 5.7.1: is this a blacklist rejection?

Choose the enhanced status code from the bounce message. Do not paste the email, recipient address or full headers. This helper explains a code; it does not inspect a message.

Read all four code explanations
5.7.1
Authorization or policy rejection. This alone does not prove a blacklist entry. Check the named list, if any, and sender authentication.
5.1.1
Invalid destination mailbox. Confirm the address with the recipient; delisting cannot correct a wrong recipient.
4.2.2
Mailbox full; temporary failure. The recipient should check quota. Avoid repeated manual sends.
4.7.0
Temporary security or policy issue. Review the server explanation and sending rate with your provider.

Automatic checks cover SpamCop and DroneBL when available. Use official checks for the other providers; retrying here does not enable their automatic access.

SpamhausBarracudaCheck mail DNS records

References: RFC 3463 · Google · Sender guidelines

Why are my emails going to spam? Four checks

Record presence cannot guarantee delivery. Use the sending domain and the actual outbound mail server.

  1. 1. Inspect mail DNS records

    Check MX, SPF and the direct DMARC record. Review missing or duplicate entries using your sending provider's instructions.

    Check MX, SPF and DMARC →

  2. 2. Read a real message's authentication results

    Inspect SPF, DKIM and DMARC in the Authentication-Results header of a received test message. This page does not test DKIM or message alignment. You do not need to upload the email here.

  3. 3. Check the sending IP

    Find the outbound IP in message headers or ask your mail provider. Your website IP and MX host may be different. An unavailable DNSBL result is unknown, not clean.

    Check IP spam blacklist results →

  4. 4. Recheck after changes

    DNS caches and TTL can delay visible changes. Recheck the records; if delivery still fails, review the receiving server's error code with your mail provider.

    Compare DNS answers →

References · Google · Email sender guidelines

FAQ

Frequently Asked Questions

Questions about network tools and interpreting results.

DNS-based Blackhole Lists (DNSBL) are real-time databases maintained by security organizations (such as SpamCop and DroneBL) that track IP addresses associated with sending spam, malware distribution, or botnet activity.