If I try to open a mailto: link in Falkon, I get the following message: " This site can’t be reached The web page at mailto:support@uber.com might be temporarily down or it may have moved permanently to a new web address. ERR_UNKNOWN_URL_SCHEME " Falkon --version output: falkon 2.1.99 (4f8b1f57)
That's bug in QtWebEngine. Will be fixed in QtWebEngine 5.11.