I remember a few months ago I got a bug-report from a customer that "their site didn't show in link-previews in MS-Teams". The URL includes a German "Umlaut": ü

I remember a few months ago I got a bug-report from a customer that "their site didn't show in link-previews in MS-Teams". The URL includes a German "Umlaut": ü After tracing the HTTP requests received from the link-preview generation on the server (logging the network packets) I found that the "Host" header wasn't the expected/configured xn--test--ova.de (IDNA to ASCII). To "work around it" I needed to add an extra VHost in Nginx with the server_name "test-\xFC.de" (that just redirected to a non-Umlaut domain). I didn't bother or even know where to report it (to MS). But apparently not using proper tooling for URL handling / HTTP requests makes one wonder about the quality of the product or even possible security implications.