Greetings to all! I am experiencing a minor annoyance with Firefox that I would like to resolve before it becomes a major PITA. I am running Firefox 93 on Linux Mint 20.1. I have email accounts with two different webmail providers: Gmail and ProtonMail. I have Gmail selected as the application I wish to use when I click a mail link on a web page. For the last couple or three months though, when I open my account on Protonmail.com, an extra window appears at the top of the Firefox window which reads "Add "mail.protonmail.com" as an application for mailto links?" This question is followed by a button labeled "Add application", but no button labeled "No, thank you", or "Bugger off", or anything similar. I can close the window by simply clicking on the close window X in the upper right corner and that is that, but ONLY for the current session. What I would like to figure out is the process by which I can 'teach' Firefox that, No! I DO NOT want to add "mail.protonmail.com" as an application for mailto links. I have looked high and low across the 'net, and particularly on Mozilla's site for an answer to my query, but I have had no joy. By involving Mozilla Support in my quest, I am hopeful that I am simply overlooking the solution to this irksome issue. I eagerly await a reply. My respect and Best Regards,