Programs based on the Sendmail Content Management API, also called Milters (short for Mail Filter), can now be run in Messaging Server. Milter provides a plug-in interface for third-party software to validate and modify messages as they pass through the MTA. Milters can process a message's connection (IP) information, envelope protocol elements, message headers, and/or message body contents, and modify a message's recipients, headers, and body. Possible uses for filters include spam rejection, virus filtering, and content control. In general, Milter seeks to address site-wide filtering concerns in a scalable way. See Using Milter in Sun Java System Messaging Server 6.3 Administration Guide.