2 answers
Violetta Chernobuk
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Hi @sanne
It's Violetta from Planyway.
Brittany shared a tip on how to get notified by emails. If you'd like teammates to receive browser, mobile or in-app notifications, you may try Planyway power-up.
Brittany Joiner
Community Leader 
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@sanne welcome to the community! i'm not sure about their email address because i don't think that's a field you can access (unless you create a custom field with that info), but you can create a comment that tags them, which should also trigger a notification and email!
You can do this by creating a rule with the action "when a member is added to a card", and the action will be post "comment" saying "@{addedusername} you've been tagged in this card!
Something like this:
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