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Fixing the 550 5.7.1 [RBL] Sender blocked <IP or domain> error

If you're receiving this error, it means your email message was sent from a server or domain that is currently listed as a high volume spam source by a reputable global block list.

How can I unblock my account as an end user?

Encourage your service provider to ensure the server you use for email sending has been secured against outgoing spam and compromised email accounts. This problem may also occur if the owner of your domain name has been using the domain for spamming or fraudulent purposes. 

Check the IP address or domain listed in the error message against reputable RBLs including Spamhaus. An excellent RBL checking tool is available at

Find out if your domain has been listed by Spamhaus using the "Domain Lookup Tool" in the URL listed below. If the domain is listed, request delisting the domain.

Secure your account against compromise by performing the following:

  • Change your password. Ensure your new password has a minimum length of eight characters and uses a mixture of upper and lower case letters, numbers, and special characters.
  • Verify that your operating system is running with the latest security updates.
  • Update your anti-virus software and conduct a full scan of your system to ensure that a spammer has not installed spam-sending malware on your computer.

If these steps do not resolve the problem, please file a support request with your web hosting provider.  

How can I unblock an end user account as a service provider?

Perform all the actions recommended above.

If you are still unable to send email, please raise a support ticket by writing to with the following details

1) Sender email address

2) Subject

3) Recipient email address

 4) Date & Time 


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  • Avatar
    Mary Clouse

    Dear Soumya,
    Please still this domain: is not delivering messages ,please help to solve this problem
    thank you

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  • Avatar
    Ultimas Noticias

    We still can't send emails, please solve

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  • Avatar
    Yan yang

    can't send emails,

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  • Avatar
    Nishchal Joshi

    Guys you can check for free whether the IP through which you're sending emails is spammy or not. Check here -> It'll check your Domain/IP with more than 100+ global email blacklists (DNSRBL) and tell you whether you're listed somewhere. You can even unlist yourself using steps given by the tool above. I did that for my website. Would recommend you to do it as well.

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    Thanks, Nishchal I find this tool very helpful and also allows us to fix the blacklist.

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  • Avatar
    Marcus Job

    One of my clients experienced something similar. So I used this tool to run a blacklist check and discovered that the client's domain was listed on the Spamhaus blocklist. Probably because the domain had a poor reputation.

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