The list of banned domains, now numbering at 9207, have sent "spam" (UCE - unsolicited commercial email) to a domain hosted by Custom Web Promotions, are known to have engaged in the activity of spamming sometime in the recent past, or email from these domains is unwelcome for various other reasons. The user of this list assumes all responsibility for any messages that were not intended to be rejected. For this reason it is highly recommended that you review the contents of this list before using it with your mail server otherwise you may end up rejecting messages that are wanted.
If you see a domain listed that you believe should not be on this blacklist, then please send email to along with the reason why you feel that the domain(s) should not be blocked. Note that you will have to use an e-mail account whose domain is not blacklisted in order for your email message to not get rejected.
The list is available in two different formats: text (domain names separated by newlines) and a text file ready to be used with the access database in Sendmail. The access file is usually found in /etc/mail on most Unix / Linux systems. Edit the access file using Vim, an improved version of the popular vi editor, or some other text editor. You will need to restart the sendmail server in order to regenerate the access.db file or use the makemap utility at the command line manually. Messages that are blocked using this list send the reject message "Sorry, that domain isn't in my list of allowed rcpthosts - see http://custweb.com/blocked_domains.html for details." to the sender of the refused mail along with an error code of 553.
We use the following software packages to help stop spam along with several realtime blackhole lists and DNS based blocking using the nameserver.
Other useful resources
