We are aware of the issue with the badge emails resending to everyone, we apologise for the inconvenience - learn more here.
When sending a file through Dropbox Transfer, you get notified everytime a file will expire within 2 days. When you send all of your work to your clients through Dropbox Transfer, you get quite a lot...
This is ridiculous. We stopped using Dropbox for transfers, because we can't handle the amount of email spam it generates.
We report the emails as spam using Office365 and in Gmail... Maybe if enough people do it, eventually they will be flagged and blocked serverside.