ITS maintains a small blacklist of hosts that pass DNS validation and have a good SenderBase reputation score but still present problems. Usually these are legitimate mail servers with technical problems, but hosts that are the source of spam, phishing, or other intentional attacks can also be placed on the blacklist. Once problems are corrected, the servers can be removed from the blacklist. System administrators whose servers have been blacklisted should contact the UT Service Desk to resolve the problem. Requests to the Help and Service Desk should include the IP address(es) of affected server(s), as well as the date and approximate time, including time zone, of the most recent incident.