High Quality Content by WIKIPEDIA articles! In computing, MXP stands for MUD eXtension Protocol. It is used in MUDs to enhance the normal text output with a markup language loosely based on HTML and XML. In order for MXP to be used it must be implemented on the server as well as on the client, and negotiated during the connection using the telnet protocol. The protocol is maintained by Zugg Software, though they have released the copyright to the public domain.