Email Blacklist Checker

Check a mail server's IP against multiple block lists — with the individual result from each source shown separately.

What is an email blacklist checker?

An email blacklist checker tells you whether the IP address of a mail server appears on spam block lists that receiving servers use to filter mail. If your sending server's address is on an email blacklist, some providers may reject your messages or send them to spam, even when the messages themselves are perfectly normal.

This tool checks the address against several DNS-based block lists and shows the result from each list separately.

How the email blacklist check works

You enter the IPv4 address of the server that sends your email. The tool reverses the address and asks each list's DNS zone whether it is listed. Three commonly referenced lists are checked: the SpamCop Blocking List, the Barracuda Reputation Block List and SORBS. Each result is Listed, Not listed or Unable to check. A failed query is reported as Unable to check and is never treated as a clean result.

This is the same check used by our IP Blacklist Checker, set out for people looking after email. It is a spot check across a few lists, not a full reputation report.

How to find your mail server's IP address

The address you need is the one that sends your outgoing mail, which is not always the address of your website.

  1. Send an email from your domain to another account, such as a free webmail address.
  2. Open the message and choose the option to show the original or the full headers.
  3. Find the earliest Received line added by your provider's server, or look for the sending IP in the authentication results.
  4. Copy that IPv4 address into the tool and press Check Blacklists.

If you use a hosted service such as Google Workspace or Microsoft 365, your mail is sent from the provider's shared servers, which they monitor and manage.

What the email blacklist results mean

Listed means the list currently includes the address. Not listed means the list confirmed it does not. Unable to check means the query failed, so that list gives no answer this time. One listing among several clean results is common, because each list uses its own evidence and rules. Check again after any fix, since lists update their entries regularly.

Protecting your sending reputation

  • Only email people who signed up, and honour unsubscribe requests quickly.
  • Send newsletters through a dedicated sending service rather than your office mail server.
  • Watch bounce rates and remove addresses that no longer exist.
  • Protect every mailbox with a strong password and two-factor login.

Common uses

  • Investigating bounces that mention a block list or a poor reputation.
  • Checking a new server or IP address before it starts sending mail.
  • Confirming a delisting request has gone through.
  • Routine checks of an office or web server that sends email.
  • Checking the address of a website server that sends order or contact-form emails.

Common problems and fixes

Your server is listed. Find out why before asking for removal: look for compromised mailboxes, malware, open relays or a website form sending spam. Once fixed, use the list's own removal page; some lists remove entries automatically after a period without new spam.

The bounce names a list not shown here. Visit that list's website and use its lookup page; the steps above for finding and fixing the cause still apply.

You entered a domain or IPv6 address. The checker accepts IPv4 addresses only. Find the IPv4 sending address in your email headers.

Related tools

Frequently asked questions

How do I know if my email server is blacklisted?

Enter your mail server's sending IPv4 address in the email blacklist checker. It queries SpamCop, Barracuda and SORBS and shows Listed or Not listed for each. Bounce messages often name the list involved, which is another strong clue about where to look.

Can I check my domain instead of an IP address?

This tool checks IP addresses, because the lists it queries track the servers that send mail. Find your sending IP in the headers of an email you sent. If you need the servers that receive mail for a domain, the MX Lookup shows them with their IP addresses.

Why is my mail server blacklisted?

Usually because spam was sent from the address, often through a hacked mailbox, malware on a device, an insecure website form or an open relay. On shared hosting, another customer may be responsible. Find and fix the cause first, or the address will probably be listed again.

How long does it take to get delisted?

It depends on the list. Some remove addresses automatically a day or so after spam stops, while others need a removal request through their website, which can take from minutes to a few days. Repeated listings usually take longer to clear.

Why is the result different from other blacklist sites?

Each tool checks its own selection of lists, and lists update constantly. A listing on a list we do not check will not appear here. Spamhaus is not included because its terms restrict use by public web tools. Check the specific list named in any bounce message directly.

I use Gmail or Outlook for business. Should I check?

Usually there is no need. Hosted providers send from their own large networks of servers, which they monitor and manage. If messages bounce, the bounce text normally explains the reason. Focus on your SPF, DKIM and DMARC records, which are under your control.

Does being on one blacklist stop all my email?

No. Each receiving provider chooses which lists to use and how much weight to give them. A listing may cause rejections at some providers and have no effect at others. It is still worth fixing quickly, because listings can spread as more lists record the same activity.