Internationalised Domain Names (IDNs) have been available since 2003 although more commonly used in the wider EMEA hosting market rather in the UK. However following feedback from a customer we've implemented Internationalised Domain Names (IDN for short) support inside STORM. This means you can use domains that use characters including é or ß. A full list of supported characters is available here.
From a technical perspective any IDN domain names are converted into Punycode before being stored in the database and configuration files. The Punycode makes the code easy to read and less likely to cause script errors.