A friend of mine was suddenly unable to log into Fastmail Classic today (June 10, 2017).
- Of course, Classic is disappearing at the end of June, but this was not his problem.
- Old versions of Firefox have a security certificate bug which shows up staring today (June 10). So you should be using FireFox v53.0.3 (released May 19). This update fixed the following bug:
https://bugzilla.mozilla.org/show_bug.cgi?id=1364240
Bill