International encoding support
When defining a new rule, the file containing the disclaimer you want to add to a message is identified. Because messages can be encoded using various regional settings, it is recommended that the files with disclaimers use UTF-8 or Unicode encoding. To create the rule it is recommended to use the built-in editor that will automatically switch the encoding to Unicode. If the file including the disclaimer text is not UTF-8 or Unicode-encoded, regional characters may display incorrectly on the recipient's machine.

If messages in non-standard encoding, such as Russian or Chinese, are sent via Exchange Server, relevant codepages have to be installed on the server to enable adding disclaimers to messages correctly.

In order to configure encoding, follow the steps described below:
1. In Microsoft Outlook menu choose Tools | Options | Mail Format | International Options.
2. The dialog such as in Fig.1 will display. Clear the Auto select encoding for outgoing messages option.
3. In the Preferred encoding for outgoing messages box select the encoding for outgoing messages, appropriate for your country. You should select the ISO encoding rather than the Windows encoding.

Correct configuration of encoding choice in Microsoft Outlook
Fig.1. Correct encoding configuration in Microsoft Outlook.

More topics:
Find out how to set the International Options for all Outlook users in the organization at Exchange.