Case Search:  
Black Listing FAQ

This article will cover the answers to frequently asked questions related to email blacklisting.

1.  What is blacklisting?

2.  How did I get blacklisted?

3.  How do I know if I am on an e-mail blacklist?

4.  How do I get removed from a blacklist?

5.  Who do I send a complaint to on practices of a blacklisting service?

6.  How can I avoid being blacklisted in the future?

7.  What are some of the common blacklisting services?

8.  How do I get additional information on blacklisting?


1. What is blacklisting?

    Blacklisting is a process of actively monitoring the Internet for reports of email traffic from a variety of sources sending unsolicited commercial email (SPAM) and then publicly listing that known information on Internet sites for others to reference as a measure to fight SPAM. Many Internet Service Providers (ISP's) and independent organizations then use these blacklist databases as a reference filter applied to their inbound mail servers to aid in preventing SPAM and to encourage internet security.

Return to top

2. How did I get blacklisted?

    There are many types of lists, but the most prevalent are the open-relay / open proxy lists, and "guilt by association" lists.

    Open-relay/Proxy server blacklists are based on open ports through which unauthorized network traffic is allowed to flow. The open-relay/proxy lists are the most definite and widely used since they are based on the presumption that a "spammer" found you and likely had relayed a high volume of SPAM through your Message Transfer Agent (MTA), causing your MTA's IP address to be reported to the list by recipients of that SPAM. Many of the better blacklists will run an automated script to verify that the evidence against you is genuine before blacklisting your server. Many blacklists will quickly de-list you if you submit a request to retest your "repaired" mail server. There will be propagation time after you are de-listed (sometimes as long as a week), because the destination mail server administrators pull the updated lists at times they prefer.

    Another method blacklist sites use to produce listings is that of "guilt by association". A blacklist site will list much larger blocks of IP addresses than those owned by the suspected abuser. For example, if you are provided with an IP address and the "spammer" owns an address that is close in range to yours and the spammer gets listed on this type of blacklist, your IP block might be listed as well. Usually the reasoning behind this practice is that, by punishing innocent parties, the blacklister is putting more pressure on the ISP to disconnect the suspected spammer's Internet access.

Return to top

3. How do I know if I am on an e-mail blacklist?

    Typically, the first clue that you may have been blacklisted is that you will receive "bounce-back" emails from the destination domain to which you are attempting to deliver mail. Many of these bounce-backs from destination mail server(s) will inform you of the technical reason that you are being blocked but some will not, depending on the administrator's preferences and type of MTA software.

    Gilardi uses the following blacklist sites. Most provide an automated test that you can run against your IP address:


    *Note: Before assuming you are listed on blacklists, make sure to check that your outbound mail server has correct forward and reverse DNS and is not an open-relay, and that other technical settings are correct by referencing your mail server software documentation.

Return to top

4. How do I get removed from a blacklist?

    Generally the most expedient way of being removed from a listing is to contact the blacklist service directly. Since blacklisting services each have their own procedures for adding and removing IP's, all complaints should be sent directly to the blacklisting service. Please visit the blacklisting services' website for more information.

Return to top

5. Who do I send a complaint to on practices of a blacklisting service?

    Since each blacklisting service has its own procedures for adding and removing IP's, all complaints should be sent to the blacklisting service. Please visit the blacklisting services' website for more information.

Return to top

6. How can I avoid being blacklisted in the future?

    There are several ways to avoid being "blacklisted".

    MAINTAIN and update your anti-virus software. Your anti-virus software manufacturer should provide helpful information on virus definitions through a "threat list". New threats of viruses are listed on a daily basis, while other viruses are re-coded and re-distributed. Some of these viruses, called worm-viruses, are self-propagating infections that embed themselves into your system files - causing the virus to send out SPAM, without your knowledge, but that appears to come from you (your IP address).

    MAINTAIN your security features on your PC or Network Servers. Open Mail Relays have become a major cause for blacklisting. An Open Relay is used as a conduit to send UCE/SPAM through your connection by spammers who, thereby, mask their identity and make it appear as if you are the originator of the message. You may find instructions on how to test for, and close, open relays by researching various blacklist and anti-spam resources.

Return to top

7. What are some of the common blacklisting services?

Return to top

8. How do I get additional information on blacklisting?

Return to top

For all other questions, please call (415) 461-0410 or our toll-free number (800) 447-7657 to speak to a customer service representative.

HomeSite MapPrivacy Policy
Copyright © 2008 Gilardi Co. LLC