I have 4 suggestions/requests for improving Exim spam filtering: 1) Allow customizing the rejection and logging messages for the custom RBL entries. Not all DNSBL replies have a TXT record. This results in a cryptic and untraceable rejection. Having a custom error message.. or including the RBL name would help the rejecting admin answer questions from the rejected admin. 2) Allow RBL sorting. Not all DNSBL systems are created equally. Some are more likely to have an answer. Putting these at the top of the list will prevent unnecessary polling of lesser but important DNSBL's 3) Add functionality for DNSWL (whitelist) that is processed prior to RBL's. Sample: accept dnslists = list.dnswl.org add_header = X-Spam-WHITELIST: YES log_message = $sender_host_address whitelisted in \ $dnslist_domain=$dnslist_value 4) Add Exim support for Spamhaus DBL Spam Assassin is capable of providing this filtering, but it is better handled at SMTP connection and can be included in EXIM without too much effort: Example: https://grepular.com/projects/EximExtractDomains Thank you for considering these suggestions. - - - Updated - - - And a bug-report: If a user inadvertently creates a custom RBL named spamcop bl.spamcop.net or spamhaus zen.spamhaus.org WHM will create the custom lists, duplicating the originals, and then not allow the custom entries to be deleted.