Opt-ou/in email notification

Whenever the user receive a notification, Hubl sends an email.

• Add a checkbox/switch on "Edit my profile" page which allows the user to opt-in/out for all email related to notifications.

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Original mesage/user story:

Apparently when someone @mentions you in a chat room, you get the message as an email.

WHOAH, please tell me that is optional, and where to administrate that.

As for this ticket: I would expect such administration to be intuitive to locate, and enabled only after an explicit consent!