When hovering over a link, email address or what not, thunderbird (probably also firefox), does not show the REAL information, it shows the "pretty" information Lets say I am trying to impersonate https://www.danfoss.com and I share the following link https://www.dánfoss.com Hovering will show https://www.dánfoss.com And gives no information to the user, that the link is forged, this is especially bad for someone who does not have 20/20 vision, the small apostrophe above the a is almost invisible. When hovering the URL it should be shown as https://www.xn--dnfoss-pta.com Now it is very trivial to see that the URL is not what it seems to be. There are many characters, where there are other character encodings that looks visually the same as the UTF-8 ones, and are even harder to visually see a difference. I would strongly suggest changing the default hover view, to show the "real address", or add to the view, so that both the "pretty" and the non-pretty is shown. Similarly when replying to an email, the mail program should also show that "you have never communicated with this email address/domain before" when replying, allowing the detecting of spoofing.
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