There should be a lot more characters after that base "safelinks" address. Maybe you removed that for privacy when posting here? If it is actually missing, I wonder whether an anti-tracking add-on might be removing it. ---- ''Since this problem just started recently:'' Firefox recently rolled out "Total Cookie Protection" to more users. This limits how sites can use "third party" cookies, meaning cookies from different websites than the one you see in the address bar. Since Microsoft uses numerous different servers for sign-in, your Inbox, and those outbound links, it's possible there is an authentication failure in this case. You can make exceptions to this feature when needed. More info in the following articles: * [[Introducing Total Cookie Protection in Standard Mode]] * [[Total Cookie Protection and website breakage FAQ]] ---- Also, "just in case", make sure the redirect block is turned off: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. (This on your Mac only, not for mobile.) (2) In the search box in the page, type or paste '''accessibility.blockautorefresh''' and pause while the list is filtered (3) If the preference has a value of true, double-click it to restore the default value of false