You have a Microsoft Exchange Server 2010 server that has the Mailbox role installed.
You configure the regional language settings of Exchange server to a language other than English.
Certain characters in the language have different uppercase and lowercase versions. For example, the lowercase character of "I" in Turkish is not "i", but a dot-less "ı".
You apply retention policies to mailboxes.
In this scenario, the retention policies are also applied to Contact items of the mailboxes unexpectedly.
This issue occurs because the Microsoft Exchange Mailbox Assistants service uses an incorrect method for item class comparison when retention policies are executed. The case-insensitive comparison fails after an uppercase to lowercase conversion. Therefore, Contact items are included in retention policies.
To resolve this issue, install the following update rollup:
2608646 Description of Update Rollup 6 for Exchange Server 2010 Service Pack 1
To work around this issue, change the locale to English (United States). To do this, follow these steps:
Click Start, and then click Run.
Type intl.cpl in the Open box, and then click OK to start Region and Language.
On the Formats tab, select English (United States) in the Format list.
On the Administrative tab, click Change system locale.
Click English (United States) in the Current system locale list, and then click OK.
Click OK in the Region and Language dialog box.
Restart the server.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about retention tags and retention policies, visit the following Microsoft website: