Mail servers protect their users by refusing email from IP addresses known for spam. They look those addresses up in DNS-based blacklists (DNSBLs). If your mail server's address is listed, your emails bounce or land in spam. Check any IPv4 address now with our Blacklist Check.
Signs your IP is blacklisted
- Bounce messages mentioning "blocked", "listed", "RBL" or a list's name.
- A sudden drop in replies, or customers saying your emails are in spam.
- Your email provider or hosting company warns you about spam from your account.
Why IP addresses get listed
| Cause | Typical fix |
|---|---|
| A computer on the network has malware that sends spam | Scan and clean all devices |
| A compromised email account sends spam | Change passwords, enable two-factor login |
| An insecure web form or script sends mail | Fix or remove the script, add a captcha |
| Open mail relay | Configure the server to relay only for authenticated users |
| No or generic reverse DNS | Set a proper PTR record |
| Sending to old, purchased or invalid lists | Use confirmed opt-in lists only |
| Dynamic home address | Normal: send through your provider's mail server instead |
How to get delisted
- Find out which lists show the address with our Blacklist Check.
- Fix the cause. Requests are refused, or the address is listed again quickly, if the problem is still there.
- Authenticate your mail with SPF, DKIM and DMARC.
- Visit each list's website and use its lookup or removal page. Most removals are free and self-service. Be wary of anyone who charges for "express delisting".
- Wait and re-check. Many lists expire entries automatically after a few days without new spam.
- Ask your hosting provider for help or a new IP if you cannot fix a shared server yourself.
How to stay off blacklists
- Monitor outgoing mail volume and alert on spikes.
- Rate-limit outgoing mail per account on your server.
- Keep software, plugins and passwords up to date.
- Remove addresses that bounce and honor unsubscribe requests immediately.
- Use a reputable email service for newsletters instead of your own server.
Blacklisted home IP?
Some lists, such as spamrats' "dyna" and "noptr" lists, include whole ranges of home addresses because legitimate mail servers rarely run on them. If you only browse and send mail through Gmail, Outlook or your provider, these listings do not affect you.
Frequently asked questions
Does a blacklist affect browsing or gaming?
Spam blacklists only affect sending email. Some websites use other reputation lists, which can cause extra captchas.
How long does delisting take?
From minutes for self-service lists to a week for lists that expire entries automatically.
Can I check IPv6 addresses?
Most blacklists only track IPv4, so our tool checks IPv4 addresses.