Being placed on a black hole list is relatively easy in today's recipient-focused e-mail client environment. There are several black hole lists out there, and an ISP can subscribe to one or all of them if it wishes. If enough people make a complaint against a server, the typical reaction is to report the server to a black hole list. If you find a sudden increase in bounced e-mail, hard or soft, or a corresponding drop in open and click-through rates, it could be the result of the mail server being placed on a black hole list.
Other reasons e-mail servers get reported are: poor bounce management, not honoring unsubscribe requests and bad sending habits, such as sending e-mail blasts too frequently or not sending what was promised. If these underlying issues are never addressed, the server will likely be listed in one place or another.
When a spike in the bounce rate occurs, it's a good idea to try to capture a bounced message or two. A professional e-mail marketing solution worth its weight usually has a debug feature that, when enabled, archives the conversation with the bounce account and logs the reason for the bounce. Another investigation option is to copy all bounced e-mail messages and forward them to a separate e-mail account, just long enough to identify in more detail the reason they bounced. You can also quickly reference black hole list check tools such as DNSstuff.com or Email Tools Blacklist check.
Typically, when there is a bounced e-mail message related to a black hole listing, the message will provide you with a link to the list. This link can explain why the server is listed. Many of the black hole lists have procedures to help an e-mailer remove a server from their lists, mostly involving providing proof that you really are not spamming. Subscription dates, e-mail policies or other data may be required before a computer can be successfully removed.
If you find that your server has made it onto a list, don't panic. Examine your e-mail behavior carefully and correct the underlying reasons that you were put there in the first place. Then contact the list managers and work with them to get the server delisted.
Jim Kinkade is the technical support supervisor at Arial Software (www.arialsoftware.com), a provider of e-mail marketing software.