Exchange 2010 SP2: Changes to the MRSProxy Service Configuration

Although it’s a minor one, it’s worth mentioning another change introduced by Exchange 2010 SP2 this time revolving around the Mailbox Replication Proxy Service (aka MRSProxy service). So as some of you know, the MRSProxy service helps facilitate cross-forest mailbox move requests. Its often used when performing a cross-forest migration from a legacy Exchange organization (containing at least one Exchange 2010 CAS server as the MRSProxy must be enabled in the source organization) to an Exchange 2010 organization. The MRSProxy makes mailbox move requests more seamless because it, among other things, encapsulates all communication between the organizations in HTTPS packets (read more details in the Exchange 2010 documentation on TechNet). If an organization decides to move to Exchange Online in Office 365 and the organization uses the rich coexistence scenario, they also use the MRSProxy, which means that its required to deploy at least one Exchange 2010 CAS server in the on-premise organization.

So up until Exchange 2010 SP2, the MRSProxy was disabled by default. And if you needed to enable it, you had to do so via the EWS “web.config” file located under “C:\Program Files\Exchange Server\V14\Client Access\exchweb\ews”.


In the bottom of this file, you needed to change IsEnabled=”false” to IsEnabled=”true” then save the file and restart the Exchange MRS service.


I’ve often wondered why the MRSProxy wasn’t enabled by default but guess this has to do with the relatively few cross-forest migrations that occur compared (at least compared to Exchange 2010 upgrades).

But now that Office 365 is here, it makes even more sense to enable it or at least make it easier to enable and disable it. Well guess what? Exchange 2010 SP2 does exactly that. With Exchange 2010 SP2, we can now enable and disable the MRSProxy using the “Set-WebServicesVirtualDirectory” cmdlet. We can also configure the MRS connection limit using this cmdlet. For instance, if I wanted to enable MRSProxy and configure a connection limit to 100, I could use this command:

Set-WebServicesVirtualDirectory -Identity "EWS (Default Web Site)" -MRSProxyEnabled $true –MRSProxyMaxConnections 100


Much easier right?

Until later,

Henrik Walther
Technology Architect/Writer/MS Vendor
MCM: Exchange Server | MVP: Exchange Architecture

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