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Apache module for Outlook Anywhere support in reverse proxy setups
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src Add support for "oldie" kernels Aug 18, 2014



mod_proxy_msrpc - Apache module for Outlook Anywhere support in reverse proxy setups


Build the module:


Load the module:

LoadModule proxy_msrpc_module /path/to/your/

Enable the module inside a <VirtualHost> configuration container (or globally):

OutlookAnywherePassthrough On


This module intends to make Apache httpd work in a reverse proxy setup in front of a MS Exchange server offering Outlook Anywhere services. Without it, Apache would block any Outlook Anywhere requests for reasons documented very well in

Outlook and Exchange use an extended version of DCE RPC called MSRPC to communicate with each other. When Outlook Anywhere is in use, the MSRPC messages are wrapped into HTTP alike requests and responses. The mod_proxy_msrpc module detects these MSRPC messages and forwards them to the server or client as needed. As soon as the initial handshake completed, i.e. Exchange accepted the connecting client, the mod_proxy_msrpc module switches into tunnel mode and forwards all data from client to server and vice versa.


Some older Exchange versions (e.g. Exchange Server 2007) are known to sync offline address books and calendar information via other protocols than Outlook Anywhere (i.e. MSRPC via HTTP). For these Exchange versions functionality of this module is limited to enabling receiving and sending mail. I.e. Address book and calendar synchronization doesn't work with these Exchange versions.


If you encounter any problems, you can set following directive:

LogLevel info proxy_msrpc:trace2

This will enable detailed debug logging for the proxy_msrpc module, which will be written to the usual Apache log destinations (e.g. to file error.log).


Please use the GitHub issue tracker to check for any pending issues or to report any new bugs.


This module was initially written by Micha Lenk as employee of Astaro GmbH & Co. KG, Germany, to facilitate Outlook Anywhere passthrough for the Sophos UTM's Web Application Firewall. It was first released as part of UTM 9.1 in May 2013. Sophos generously agreed to contribute the source code to the open source community under the terms of the Apache License 2.0.


This module was written by Micha Lenk <>.


Copyright 2013 Micha Lenk <>, Astaro GmbH & Co. KG - a Sophos company.


This module is free software; you may redistribute it and/or modify it under the terms of the Apache License, Version 2.0. You may obtain a copy of the License at

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