Thursday , June 11 2020

Site to site proxying with one Internet facing Exchange server

Scenario – Site to site proxying with one Internet facing Exchange 2010 server

Site 1 (Primary) – Exchange 2010 sp3 Server (Internet Facing Server)

Site 2 (Secondary) – Exchange 2010 sp3 Server (Non- Internet Facing Server)


Now Primary Site being an internet facing site. It will receive all the emails from Internet and give to the secondary site.

Sending email to the internet can’t be independent on Secondary site. As secondary site is not internet facing.


  • Its case to case basis sometimes we are forced to do this as secondary site has only ADSL connectivity.
  • Companies who needs unified URL.
  • Companies wants to send out emails only from Primary site for compliance purposes.

Cons :

  • If any issues on Primary Site Connectivity , External mail flow stops.
  • If external users are high from secondary site ,WAN utilization may increase from primary to secondary site.

lets see how to do this.

We will set all the external Urls to $null in Secondary Site.

Set-OwaVirtualDirectory –Server "Servername" –externalUrl $null
Get-OwaVirtualDirectory | fl Server,Internalurl,ExternalUrl


Get-WebServicesVirtualDirectory | fl Server,Internalurl,ExternalUrl


Get-ECPVirtualDirectory | fl Server,Internalurl,ExternalUrl


Get-ActiveSyncVirtualDirectory | Fl Server,Internalurl,ExternalUrl


Properties of Owa virtual directory in secondary site –

Integrated Windows Authentication should be checked.


Outlook anywhere in Site B should be in disabled state –


Now – Active Sync / Outlook anywhere/ Outlook Web app started working from Primary site proxy to secondary site.

There are no InternalURL or ExternalURL settings for the POP3 or IMAP4 services in Exchange 2010 Client Access server

POP3 and IMAP4 service requests can proxy from one server to another,

Make sure all Exchange 2010 servers have POP and IMAP enabled,As Exchange just proxy the request it wont check its enabled or disabled on the other site.

About Satheshwaran Manoharan

Satheshwaran Manoharan is an Microsoft Office Server and Services MVP , Publisher of Specialized in Office365 / Microsoft Exchange / Virtualization , Sathesh is an Messaging Expert supporting/Designing/Deploying many medium size businesses to large enterprises when it comes to Corporate messaging and Virtualization Infrastructure

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One comment

  1. Damn, this is all I was looking for, Great article for cross site proxing – you are the best Sathish

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