Force encoding with IIS 7

Solution 1:

You can manually set the content type for specific file extensions in the web.config file for each web site where this is needed. In the root for the site, find the web.config file and add the remove and mimeMap lines as below (or create the entire file if it doesn't already exist).

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <staticContent>
            <remove fileExtension=".html" />
            <mimeMap fileExtension=".html" mimeType="text/html; charset=UTF-8" />
        </staticContent>
    </system.webServer>
</configuration>

Sample taken from a discussion on the IIS Forums which addressed this question.