Exchange 2013 SP1 Mapi over Http (MapiHttp)

Microsoft Exchange team announced general availability of service pack 1 for Exchange Server 2013 on 24th Feb this month. Exchange 2013 SP1 ships with some new additions. MapiHttp is one of the interesting additions from the client connectivity standpoint which improves the stability and reliability of outlook clients to an exchange 2013 SP1 server. MapiHttp seems to be a replacement to the traditional RPC/HTTPS protocol for the clients. RPC/HTTPS has been around the exchange builds since Exchange 2003 and has worked well with outlook clients with few exceptions related to stability. Since RPC traffic is encapsulated inside the HTTPS packets, a RPC proxy was always needed for RPC/HTTPS to work. Although RPC/HTTPS has worked in almost every deployment, it is not very stable to be reliant upon when one uses an internet connection that too unstable. RPC is known to be a thick protocol and is not meant to be running on slower or unstable connections.

Mapi over HTTP removes the RPC protocol completely and moves the client-server traffic over an industry standard HTTP protocol leveraging several functions of windows http client that supports pause and resume capabilities. This gives a the clients a new capability to change networks or resume from hibernations while maintaining the same server context much faster than traditional RPC/HTTPS communications.

Things you should know as an administrator

We have a new protocol that looks similar to RPC/HTTPS but more efficient and flexible but be advised that this is currently available for Outlook 2013 with SP1 and Exchange Server 2013 with SP1 only. Below table describes how other clients will still connect to an Exchange 2013 SP1 based server.

Product Exchange 2013 SP1 Exchange 2013 RTM Exchange 2010 SP3 Exchange 2007 SP3

Outlook 2013 SP1

  • MAPI over HTTP
  • Outlook Anywhere

Outlook Anywhere

  • RPC
  • Outlook Anywhere
  • RPC
  • Outlook Anywhere

Outlook 2013 RTM

Outlook Anywhere

Outlook Anywhere

  • RPC
  • Outlook Anywhere
  • RPC
  • Outlook Anywhere

Outlook 2010

Outlook Anywhere

Outlook Anywhere

  • RPC
  • Outlook Anywhere
  • RPC
  • Outlook Anywhere

Outlook 2007

Outlook Anywhere

Outlook Anywhere

  • RPC
  • Outlook Anywhere
  • RPC
  • Outlook Anywhere
  • Mapi over HTTP is still a new thing in era at the moment. I would recommend not implementing it in production without testing in lab environments.
  • Mapi over HTTP is an organization level setting and can be enabled and can be enabled by using Set-OrganizationConfig –MapiHttpEnabled:$True and all client access servers running Exchange 2013 SP1 must be upgraded Exchange Server 2013 SP1 before enabling this setting.
  • Outlook clients may experience disconnection or may require a restart after you enable this setting. My lab required me to restart outlook after the outlook client threw an error pop up saying it needed to be restarted since an administrator has made some changes.
  • Although the setting is enabled at organization level, configuration is to be done on the server level. Exchange 2013 service pack 1 installer creates a new virtual directory called “mapi” is IIS and an associated object in active directory. You must configure the virtual directories using Set-MapiVirtualDirectory to set InternalUrl and ExternalUrl on individual servers. Ensure the certificate used on Exchange server matches the internal and external url parameter values.
  • Make sure that the servers have enough space to accommodate the log files generated by the connections. Mapi over HTTP logs are generated and stored at:
    • %ExchangeInstallPath%\Logging\MAPI Address Book Service\
    • %ExchangeInstallPath%\Logging\MAPI Client Access\
    • %ExchangeInstallPath%\Logging\HttpProxy\Mapi\

In addition to this post I strongly recommend spending few minutes in reading and watching below:

MAPI over HTTP

Exchange 2013 and MapiHttp

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