SORBS Spam Blacklist:
What it is & How to Delist Yourself

Learn about the Sorbs Spam Blacklist, how blacklists work and why they work, and how to keep out of spam in this article.
Are you finding that certain emails and contact forms are being blocked?

You may have been placed on the SORBS Spam Blacklist.

This can be a discouraging experience for any company using email marketing or cold emailing to reach their target audience, but there is no need to worry.

This blog post'll cover the SORBS spam blacklist and how to delist yourself so your messages don't go unnoticed.

What is SORBS Spam Blacklist?

SORBS (Spam and Open-Relay Blocking System) is a widely used spam-blocking service and DNS-based blacklist designed to identify and block email messages from known sources of spam and open mail relays that spammers can manipulate.

The SORBS blacklist maintains a database of IP addresses reported or identified as spam sources. When an email server checks incoming messages against the SORBS blacklist, it queries the SORBS DNS servers to determine if the sending IP address is listed. If the IP address is found in the SORBS database, the email server can take appropriate action, such as rejecting the message or marking it as spam.

In addition to identifying spam sources, SORBS detects and lists IP addresses associated with open mail relays. Open relays are mail servers allowing anyone to send emails, regardless of affiliation or authorization. Spammers often exploit open relays to send large spam emails while hiding their trustworthy source.

Reasons You Might be Blacklisted on SORBS

Insecure Email Server

An insecure email server can be a reason for someone to be blacklisted on SORBS. One common issue is the presence of an open relay. An open relay is an email server configuration that allows anyone to send emails through it, regardless of authentication or authorization. Spammers frequently use open relays to distribute vast amounts of unsolicited emails, leading to a negative reputation for the associated IP address. SORBS actively identifies and lists IP addresses associated with open relays. If an email server is found to be operating as an open relay, it is likely to be blacklisted.

Another security vulnerability that can lead to blacklisting on SORBS is weak or nonexistent spam filtering measures. If an email server lacks effective spam filtering mechanisms, it becomes an attractive target for spammers. As a result, the server may inadvertently allow a significant volume of spam emails to be sent from its IP address, which can trigger SORBS to blacklist it. In this case, the server's lack of adequate security measures contributes to its compromised reputation and subsequent inclusion on the SORBS blacklist.

An insecure email server may also be compromised by unauthorized access or abuse. If an attacker gains control of the server or exploits vulnerabilities within its configuration, they can use it as a platform to send spam emails. Such unauthorized activity can quickly lead to the server's IP address being reported and subsequently blacklisted on SORBS. It underscores the importance of maintaining robust security practices and promptly addressing vulnerabilities to prevent unauthorized access and potential blacklisting on spam-related databases like SORBS.

Infection With Trojans

Trojans are malicious software that can infiltrate a computer system and grant unauthorized access to an attacker. When a computer or server becomes infected with trojans, it can be exploited to facilitate spamming activities.

They can be programmed to use infected machines as part of a botnet, a compromised network controlled by a malicious entity. These botnets can be used to send out massive volumes of spam emails without the knowledge or consent of the device owner. When an infected device, including an email server, is involved in spamming activities, it may end up on the SORBS spam blacklist.

Once an email server is identified as a source of spam, either due to a trojan infection or being part of a botnet, SORBS may list the associated IP address. This listing warns other email servers and administrators to exercise caution when receiving emails from that IP address. Being listed on the SORBS spam blacklist can have significant consequences, including an increased likelihood of legitimate emails being flagged as spam or rejected altogether by servers consulting the blacklist.

Frequent Spam

When an individual or organization consistently sends a significant volume of unsolicited and unwanted emails, they can earn a negative reputation as a source of spam. SORBS actively monitors and identifies such behavior, leading to the listing of IP addresses associated with frequent spam-sending.

Spammers often use various techniques to send mass amounts of spam emails, including using compromised or dedicated servers solely for the purpose of spamming. If the spammer's activities are detected, reported, or observed by SORBS or its contributors, the associated IP address can be added to the SORBS spam blacklist.

Being listed on the SORBS spam blacklist has consequences for the sender. Email servers and providers consult this blacklist to help identify and filter out spam. Suppose an IP address is on the SORBS blacklist. In that case, email messages originating from that address are more likely to be flagged as spam or rejected by recipient servers relying on SORBS as a reference.
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How to Remove Yourself From SORBS Spam Blacklist

A single IP removal policy is difficult to define due to the high number of zones that SORBS hosts. Aside from administrative error, specific lists are static and will never have the IP addresses erased. The blacklists for dynamic IP addresses are one instance of this.

Others, like the open relay blacklists, won't delete your IP until your system has been secured and your IP has passed an open relay check. Your IP address can be removed from the blacklist, but almost always, if you correct whatever it was, that was causing spam.

SORBS offers comprehensive tools to assist you in figuring out why you were stopped, access to mailing lists, and administrators eager to teach you how to make your SMTP server more secure.

You can ask to be removed from the SORBS Spam Blacklist. The steps to do so are as follows:

  1. Check your IP address: Determine the IP address that SORBS have blacklisted. You can usually find this information in your email server logs or by using online IP lookup tools.
  2. Identify the reason for blacklisting: Understand the reason for the blacklisting, such as frequent spam-sending or other suspicious activities associated with your IP address. This will help you address the issue more effectively.
  3. Take corrective measures: Once you have identified the reason for blacklisting, take appropriate corrective measures to resolve the issue. This might involve securing your email server, updating security software, implementing stronger spam filters, or addressing compromised accounts or vulnerabilities.
  4. Contact SORBS: Visit the SORBS website and look for their delisting procedures or contact information. Following SORBS's guidelines for delisting from their spam blacklist is crucial. They may require specific information or actions, such as filling out a delisting request form or providing evidence of corrective measures.
  5. Provide necessary information: Prepare the required information, including your IP address, evidence of corrective actions taken, and any additional details requested. Be clear and concise in explaining the steps you have taken to resolve the issue and prevent future occurrences.
  6. Submit delisting request: Follow the designated process for submitting a delisting request. This may involve completing an online form or emailing the necessary information. Ensure that you provide all the requested details accurately.
  7. Monitor the status: After submitting the delisting request, monitor your email server's reputation and delivery rates. Keep an eye on any communication from SORBS regarding the delisting process or any additional actions required from your side.
  8. Follow up if needed: If you don't receive a response or your IP address is not delisted within a reasonable timeframe, you may need to follow up with SORBS. Contact their support or delisting team again, politely inquire about the status, and provide any additional information they may require.


Wrapping up, SORBS is a highly aggressive blacklist that can filter out legitimate emails from your server. If your emails start being filtered through SORBS, it’s crucial to investigate the matter and get your IP delisted as soon as possible.

As mentioned in this blog post, there are many ways to do so – request your ISP to change the sender IP address or vouch for your business per support appeal criteria set by SORBS.

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