Browser-specific redirection error...
If you use the link in the emails to unsubscribe from a thread (my email is from read on outlook.com) and use Linux Mint 18.1/Firefox 53.3.x and you are ME, you get an invalid link error (outlook.com).
Doing the same thing from IE 11 works with no problem. If you were to click on the unsubscribe link again in IE you would normally get an invalid thread type error...
Since I had to go on the Windows box and open Outlook email to chack this out, it wasn't specifically from having two instances open at the same time.
This is also a new problem as last week's notifications behaved properly in this respect either way.
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