Having run the same question, I found the answer here (for IIS7 / 7.5, but expect this to work for Casini too):
Or:
- Directly add
; charset=utf-8to the mime type in the mine type configuration in IIS Manager. - Edit the web.config file:
<configuration>
<system.webServer>
<staticContent>
<mimeMap fileExtension = ". rss" mimeType = "text / xml; charset = utf-8" />
</staticContent>
[...]