Symptoms

Consider the following scenario:

  • You install Microsoft Exchange Server 2010 Service Pack 1 (SP1) in Hosting mode by using the /hosting switch.

  • You create two tenant organizations (organization 1 and organization 2) in the Exchange Server 2010 SP1 environment.

  • Organization 1 has a mail-enabled user (user A).

  • You create an external contact for user A in organization 2.

  • The administrator of organization 1 tries to manage the mailbox of user A by using the Exchange Control Panel (ECP).

In this scenario, the administrator receives an ECP dialog box that contains the following error message:

More than one mailbox has the same e-mail address. To resolve this issue, contact your administrator.

Cause

This issue occurs because the ECP incorrectly looks up the user by using a global scope. Therefore, two objects that have the same Simple Mail Transfer Protocol (SMTP) address are found.

Resolution

To resolve this issue, install the following update rollup:

2661854 Description of Update Rollup 2 for Exchange Server 2010 Service Pack 2

Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

For more information about multi-tenant Exchange deployments, visit the following Microsoft website:

General information about multi-tenant Exchange deploymentsFor more information about the Hosting mode, visit the following Microsoft website:

General information about the Hosting modeFor more information about how to create a tenant organization, visit the following Microsoft website:

How to create a tenant organizationFor more information about the New-MailContact cmdlet, visit the following Microsoft website:

General information about the New-MailContact cmdlet

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