Out of the box, Laravel comes with the ability to generate "signed" URLs. These URLs have a hash in their query string that verifies that the URL was not modified.
At Flare, we use these signed URLs to add action links in mail notifications. The action links allow users to snooze and resolve errors right from the mail without having to be logged in. Pretty convenient!
My buddy Dries Vints noticed a slight drawback. He got a mail from Flare that contains these action links. A few hours after the mail arrived, he clicked one of the action links. This is what he saw.