give users control over frequency of emails+issues

My flow around emails re card changes is to notice there are one+ changes recently, delete all of them, and go check recent changes. It would be a welcome relief if I could set it so that I get one email a day from each Wagn that has changes, listing all changes at once.

Need to think through how granular/broad to make this, and how to divide things up if they are granular - there could be one setting that applies to all emails, or have separate settings for notifications, account requests, flexmails...?