http://sn.1w6.org/file/bobjonkman-20160902T220721-kc3h4er.html

The OS runs a Desktop Notification Service which each application accesses independently. I think this is the specification for the Desktop Notification Service: http://www.galago-project.org/specs/notification/0.9/ Each application has its own allow/disallow setting for notifications, so even if you disallow your mail client to send notifications, your browser may still be allowed to send notifications. A browser may even have allow/disallow settings for individual web pages, such as in Opera. http://sn.jonkman.ca/attachment/32916