What causes an IP to be listed on CBL and how can it be resolved?

Email marketer from SparkPost shares that CBL listings often stem from compromised devices or malware infections sending unsolicited emails. To resolve this, they recommend identifying and removing the source of the spam, then requesting delisting through the CBL's website.

Marketer from Email Geeks shares a reply from John Levine explaining that nothing is infected and that the issue was caused by a random survey of .org domain web pages hitting a C&C sinkhole, leading to a false alarm listing.

Email marketer from Reddit's r/emaildeliverability notes that poor sending practices, like sending a high volume of emails without proper authentication or engagement tracking, can lead to blacklisting.

Email marketer from Reddit's r/emailmarketing explains that hitting spam traps is a key reason for blacklisting. These traps are email addresses used to identify spammers, and sending to them damages your reputation.

Email marketer from Mailjet explains that being listed on the CBL can be caused by compromised credentials, malware infections, or sending spam-like content. They advise scanning systems for malware, securing accounts, and reviewing sending practices.

Email marketer from Website Defender Blog shares that unpatched web server vulnerabilities can be exploited to send spam, leading to IP blacklisting. Regularly update your server software and implement security measures.

Email marketer from Email Marketing Forum discusses that a sudden CBL listing can be due to a recent malware infection on a server, resulting in a spam outbreak. Running a full security scan is essential.

Email marketer from Security Tips Website explains that compromised email accounts can be used to send spam without your knowledge, resulting in your IP being blacklisted. Implement strong passwords and enable two-factor authentication.

Email marketer from Email Marketing Forum explains that using a reputable email list cleaning service can prevent sending to invalid or spam trap addresses, which can help avoid being blacklisted.

Email marketer from SendPulse states that being on a blacklist like CBL can be a result of a high spam complaint rate, sending to invalid email addresses, or compromised accounts. To fix this, they suggest cleaning your email list, improving email content, and authenticating your sending domain.

Expert from Email Geeks shares that the system is infected with something and it’s listed on the CBL and the user needs to fix whatever is infected.

Expert from Word to the Wise emphasizes the importance of monitoring your IP reputation and promptly addressing any issues to avoid prolonged blacklisting. Regularly check if your IP is listed on major blocklists and take immediate action if found.

Experts from Email Geeks clarified that the issue was not an infected machine and that it should be fixed by John.

Expert from Email Geeks suggests emailing John to let him know he needs to look at this and also provides John's email.

Expert from Email Geeks explains that the IP is a CBL listing which should self resolve once the system sending spam is shutdown.

Expert from Spam Resource suggests monitoring outbound email traffic for unusual patterns that indicate a compromise. Implement alerts for suspicious activity and quickly investigate any anomalies.

Documentation from Barracuda Networks shares that to avoid blacklisting, ensure proper email authentication (SPF, DKIM, DMARC), maintain clean mailing lists, and monitor your IP reputation. Avoid sending unsolicited emails and respect unsubscribe requests.

Documentation from MultiRBL shares that listings on the CBL will often result in emails being rejected by receiving mail servers. MultiRBL is used to check an IP's status across many different RBLs.

Documentation from Composite Blocking List (CBL) explains that for most listings, the CBL automatically delists an IP address within a short period (usually hours) after the abusive traffic stops. However, some listings may require manual intervention, especially if the issue is complex or persistent.

Documentation from Composite Blocking List (CBL) explains that compromised computers exhibiting bot-like behavior, open proxies, or infected with malware that attempts to send spam directly into the internet are listed on the CBL. Exploited machines sending spam or any kind of unsolicited email, including those running software that aggressively scans the network for vulnerabilities, can trigger a listing.

Documentation from Spamhaus explains that IPs are listed due to involvement in spamming activities, hosting malware, or being part of a botnet. Spamhaus combines multiple threat feeds and human analysis to maintain its blocklists.