Mail server blacklist

A mail server blacklist, also known as a DNSBL (Domain Name System Blackhole List), is a list of IP addresses or domains that have been identified as sending spam or other unwanted emails. Mail servers and email providers use these blacklists to filter out emails from known spammers and reduce the amount of spam that reaches their users.

Here are some popular mail server blacklists:

  1. Spamhaus: One of the most well-known and widely used blacklists, Spamhaus has been tracking spam since 1998. It has multiple lists, including the SBL (Spamhaus Blocklist), XBL (Spamhaus XBL), and PBL (Spamhaus Policy Blocklist).
  2. Sender Score: Developed by Return Path, Sender Score is a reputation-based blacklist that evaluates the sending behavior of IP addresses and domains.
  3. SURBL: The Spam and UCE Reporting Blocklist (SURBL) is a DNSBL that focuses on blocking spam and unwanted emails.
  4. DNSWL: The Domain Name System White List (DNSWL) is a blacklist that identifies legitimate senders and allows them to bypass spam filters.
  5. RBL: The Real-time Blackhole List (RBL) is a DNSBL that tracks IP addresses and domains associated with spamming activity.
  6. SORBS: The Spam and Open Relay Blocking System (SORBS) is a DNSBL that blocks IP addresses and domains associated with spamming and open relaying.
  7. Mailspike: Mailspike is a DNSBL that tracks IP addresses and domains associated with spamming and other unwanted email activity.

To avoid being listed on a mail server blacklist, it's essential to maintain good email sending practices, such as:

  1. Authenticating emails: Use SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) to authenticate emails and prevent spoofing.
  2. Monitoring email sending: Regularly monitor your email sending activity to detect and prevent spamming.
  3. Keeping email lists clean: Ensure your email lists are clean and up-to-date, and that you have permission to send emails to each recipient.
  4. Complying with anti-spam laws: Familiarize yourself with anti-spam laws and regulations, such as the CAN-SPAM Act in the United States, and comply with them.
  5. Reporting spam: Report any spam emails you receive to the relevant authorities, such as the Federal Trade Commission (FTC) or the Anti-Phishing Working Group (APWG).

By following these best practices, you can reduce the risk of being listed on a mail server blacklist and maintain a good reputation as an email sender.