MAPI - Messaging Application Programming Interface

(From Wikipedia) 

In simple: MAPI is a COM-based API for MS windows for message transferring.  It is implemented by using RPC.

 

Messaging Application Programming Interface (MAPI) is a messaging architecture and aComponent Object Model basedAPI for Microsoft Windows. MAPI allows client programmes to become (e-mail) messaging-enabled, -aware, or -based bycalling MAPI subsystem routines that interface with certain messaging servers. While MAPI is designed to be independent of the protocol, it is usually used withMAPI/RPC, the proprietary protocol that Microsoft Outlook uses to communicate with Microsoft Exchange.

Simple MAPI is a subset of 12 functions which enable developers to add basic messaging functionality. Extended MAPI allows complete control over the messaging system on the client computer, creation and management of messages, management of the client mailbox, service providers, and so forth. Simple MAPI ships with Microsoft Windows as part of Outlook Express/Windows Mail while the full Extended MAPI ships withOffice Outlook andExchange.

In addition to the Extended MAPI client interface, programming calls can be made indirectly through theSimple MAPI API client interface, through the Common Messaging Calls (CMC) API client interface, or by the object-basedCDO Library interface. These three methods are easier to use and designed for less complex messaging-enabled and -aware applications. (Simple MAPI and CMC were removed from Exchange 2003.)

MAPI was originally designed by Microsoft. The company founded its MS Mail team in 1987, but it was not until it acquiredConsumers Software in 1991 to obtainNetwork Courier that it had a messaging product. Reworked, it was sold as MS PC Mail (orMicrosoft Mail for PC Networking). The basic API to MS PC Mail was known as MAPI version 0 (orMAPI0). MAPI uses functions loosely based on the X.400 XAPIA standard.

MAPI includes facilities to access message transports, message stores, and directories.

 

Service provider interface

The full Extended MAPI interface is required for interfacing messaging-based services to client applications such as Outlook. For example, several non-Microsoft e-mail server product vendors created "MAPI service providers" to allow their products to be accessed via Outlook. Notable examples include Axigen Mail Server, Kerio Connect,Scalix, Zimbra, HP OpenMail, IBM Lotus Notes, Zarafa, and Bynari.

MAPI also had a service provider interface of sorts. Microsoft used this to interface MS Mail to an email system based onXenix, for internal use.

Extended MAPI is the main e-mail data access method used by Outlook, to interface toMicrosoft Exchange, via MAPI service providers shipped with Outlook

 

MAPI/RPC protocol details

Microsoft has released full details of the MAPI/RPC protocol.^[1]

"MAPI protocol" is a colloquial name for the MAPI/RPC. At times, Microsoft has also called it "Exchange RPC" and "Outlook-Exchange Transport Protocol".

 

Open Source MAPI implementations

Up until recently Open Source implementations of MAPI have been scarce. But there are at least three open source projects working on implementing the MAPI protocol infree open source software (FOSS) libraries for use in other open source applications. This list includes theOpenMapi project,^[2] theZarafa's MAPI4Linux (also part ofOpenMapi) and the libmapi^[3] subproject of theOpenChange^[4] project which is utilized in another OpenChange subproject calledEvolution-MAPI.^[5] Evolution-MAPI is a connector provider that can be installed within the popular open sourceEvolution groupware client.

 

External links

• Messaging API at MSDN Library
• OpenChange project - details of MAPI protocol and tools for exploring MAPI protocol
• OpenMapi project - Open Source, multi-language MAPI implementation which can connect to other groupware sources, with API documentation
• Messaging API Archived User Forum