MAPI over HTTP is a new and improved method of connectivity that has been designed in Exchange 2013 SP1 to establish a stronger connection with Outlook email client. Now, you would probably ask yourself that why would Exchange introduce something that is already existing and quite fulfilled by RPC over HTTP connectivity?

Well, the architecture of RPC over HTTP connectivity (or Outlook Anywhere) was originally designed for an earlier generation of connectivity, but the present reality is to meet the diverse and dynamic challenges of a variety of network types. Today’s users prefer to connect their Outlook mail from home network, cellular network, on in-flight wireless network or wherever and whenever possible.


This is where, MAPI over HTTP connectivity comes into play and help in enhancing the user experience from all possible types of connections, even when the network falls packets in transit. You can actually see the difference, from exactly the moment you launch the Outlook application and where a message is displayed: “Connecting to Outlook” in Outlook Status bar. The MAPI over HTTP can simply minimize the amount of time for Outlook application to synchronize in just 30 seconds, where it usually consumes up to 90 seconds in Outlook Anywhere (RPC over HTTP) connectivity.


MAPI over HTTP is a long-standing replacement for Outlook Anywhere connectivity as it eliminates the intricacy involved on the dependency of RPC over HTTP and its RPC technology. MAPI over HTTP is purely based upon request/response pattern and no longer involves the two TCP connections for each session opened between Exchange and Outlook. It removes the need to have two RPC_DATA_IN and RPC_DATA_OUT connections which were essential in the past for each RPC over HTTP session. However, MAPI over HTTP is expected to produce a maximum of two current connections, i.e. one for long-lived connection and other for short-lived connection.

MAPI over HTTP vs. Outlook Anywhere

MAPI uses double-wrapped architectural design in Outlook Anywhere connectivity, which adds complexity in communication with Exchange. Another drawback associated with RPC over HTTP connectivity is that whenever a network connection is lost between the client and the server, the session gets invalid and it has to be reestablished completely all again. This method of connectivity seems expensive, tedious and time-consuming.


Where MAPI over HTTP removes this complexity of RPC encapsulation within HTTP packets. Here, MAPI uses single-wrapped architectural design, offering a clear and predictable HTTP payload. When the network is lost in this connectivity, then if it is not reset within 15 minutes, then the user can simply reconnect and resume from where it was left, without creating any interruption.


BENEFITS OF MAPI over HTTP Connectivity

Following are the benefits of MAPI over HTTP connectivity:

  • Supports authentication by deploying an HTTP based protocol
  • Offers independent session context, which does not require any dependency upon the connection. Even if the user switches the network, the server sustains the session context for a specific period of time.
  • Faster and smoother reestablishment of connection, when the connection is lost because of TCP connection for the following reasons:

a) Switching from wired to cellular or wireless network

b) Device hibernation


Upon reading the benefits of MAPI over HTTP connectivity, you may be eager to enable this MAPI/HTTP connectivity. But make sure, you meet the following supported client server requirements.

  • Client Requirements: In order to enable this MAPI over HTTP connectivity, make sure you have Office 365 ProPlus or you have Office 2013 SP1 email client. Although, Office 2010 is even supported by this MAPI/HTTP, but the prior versions of Outlook will only support Outlook Anywhere connectivity.
  • Server Requirements: To smoothly access the advantages of MAPI over HTTP connectivity, you need to update to Exchange Server version 2013 SP1 or other subsequent versions.

By using MAPI over HTTP connectivity, the users can simply eliminate the dependency upon RPC based technology. This allows Outlook to enable multi-factor authentication for users working in Office 365 and also provides the path of extensibility of the connection possibilities.

To get more information, visit