Test-OutlookWebServices failed to find the mailbox in Exchange 2010

When you try to run the Test-OutlookWebServices script on a newly installed Exchange 2010 Server, the following error may occur in the Exchange Management Shell (EMS):

[PS] C:\Windows\system32>Test-OutlookWebServices -ClientAccessServer EXCH2K10
WARNING: An unexpected error has occurred and a Watson dump is being generated: Failed to find the mailbox. Mailbox = ‘extest_acddf2d5e4954@my.domain.com’.
Failed to find the mailbox. Mailbox = ‘extest_acddf2d5e4954@my.domain.com’.
    + CategoryInfo          : NotSpecified: (:) [Test-OutlookWebServices], MailboxNotFoundException
    + FullyQualifiedErrorId : Microsoft.Exchange.Monitoring.MailboxNotFoundException,Microsoft.Exchange.Management.SystemConfigurationTasks.TestOutlookWebServicesTask

If this is the first time you try to run the test, this typically means you haven’t configured the test account yet.
You should run the new-TestCasConnectivityUser.ps1 script first. Follow these instructions to make it work:

  1. Open a Exchange Management Shell on the Exchange Server
  2. Navigate to C:\Program Files\Microsoft\Exchange Server\V14\ (or any other folder where you installed Exchange
  3. Navigate to the folder Scripts
  4. Run .\new-TestCasConnectivityUser.ps1
  5. When asked, type a strong password (Exchange 2010 will change this password automatically at a later time)

Now, you can run the Test-OutlookWebServices -ClientAccessServer <servername> again.

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8 Comments on "Test-OutlookWebServices failed to find the mailbox in Exchange 2010"

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A variable that cannot be referenced in restricted language mode or a Data section is being referenced. Variables that
can be referenced include the following: $PSCulture, $PSUICulture, $true, $false, and $null.
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : VariableReferenceNotSupportedInDataSection


I found that editing the script and replacing each instance of
-ErrorVariable err
-ErrorVariable $err
got rid of this problem.

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Jeff Green

It’s important to note this command will fail if you have multiple OUs with the same name. In this instance I had a “Users” OU somewhere else in my hierarchy so I had to edit the .ps1 script and search for $OrganizationalUnit = “Users” and change it to the DN of the root Users OU and it worked perfectly. Thanks for the post!

Muthunallu Raja G

It worked exactly, Thank you Christian.

Merry Christmas…!!


you need to do this from the mailbox server


got a write error when attempting this

Muthunallu Raja G

Hello James,

You have to type exactly in exchange Powershell as below.