Domains with umlauts have to be converted by your WWW- und FTP-Servern im Internet abzurufen. Bekannte Browser sind Netscape Navigator, Microsoft Internet Explorer, Opera und Mosaic.">browser, eMail client etc. (martin-möller.com becomes xn--martin-mller-07a4e.com). For this purpose some programs need an additional program (plugin).

Mozilla FireFox and Thunderbird on the other hand don't need a plugin and can handle umlaut domains by default.

IDN is supported since Internet Explorer 7, too.