<whatsthis>Some emails, especially those generated automatically, do not specify the character encoding which needs to be used to properly display them. In such cases a fallback character encoding will be used, which you can configure here. Set it to the character encoding most commonly used in your part of the world. As a default the encoding configured for the whole system is used.</whatsthis>
<whatsthis>Changing this from its default 'Auto' will force the use of the specified encoding for all emails, regardless of what they specify themselves.</whatsthis>