Message Posting Protocol (MPP) is used by Mail.ru Agent, a popular instant messaging program used mainly in Russia. Besides basic IM functionality (presence, contact list, sending text messages, file transfers, message history, etc) M-Agent also provides online gaming, peer-to-peer voice calls, video calls, low-rate VoIP calls, free SMS, automatic mail checking and other useful features. Mail.ru Agent communicates with its server using proprietary (but documented) protocol called MPP that works over TCP/IP. Mail.ru Agent uses portal e-mail address as unique user ID.
- Official Documentation (Page is in Russian) - Documentation may not be completable with GPL or other Licenses