You create some recipients by using Exchange Management Console or Exchange Management Shell in a Microsoft Exchange Server 2010 environment. Or, you enable some mailboxes to cloud by running the Enable-RemoteMailbox cmdlet from a Microsoft Exchange Server 2013 on-premises environment.
The aliases of the recipients begin with one of the following combinations of lowercase characters followed by numbers or combination of numbers and letter 'a' to 'f':
For example, the alias is sa000c1 or s123456.
You create an email address policy and apply the policy to the recipients.
In this scenario, the email address policy does not generate the email addresses of the recipients correctly. For example, the secondary email address of the recipients is not generated.
This issue occurs because these aliases match a special pattern. Therefore, they are recognized as randomized proxy names incorrectly.
To resolve this issue in Exchange Server 2010, install the following cumulative update:
2661854 Description of Update Rollup 2 for Exchange Server 2010 Service Pack 2
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
After you install the cumulative update, to have us enable this update for you, go to the "Fix it for me" section. If you prefer to enable this update yourself, go to the "Let me fix it myself" section.
Fix it for me
To enable this update automatically, click the Fix it button or link. Then click Run in the File Download dialog box, and follow the steps in the Fix it wizard.
Install update that is described in Microsoft Knowledge Base (KB) article 2661854 before you run this Fix it solution.
This wizard may be in English only. However, the automatic fix also works for other language versions of Windows.
If you are not on the computer that has the problem, save the Fix it solution to a flash drive or a CD and then run it on the computer that has the problem.