I just checked in a feature that puts a cap on the number of emails we can send a user per day.
Out of the box
max_emails_per_day_per_user of 100 emails per day is applied. You may bypass this limit by setting it to 0 or make it bigger.
When a user hits the limit we will display
WARNING: you reached the limit of 100 daily emails. Further emails notifications will be suppressed.
This is displayed at the bottom of the 100th emails.
Cap does not apply to “forgot password” (where a different cap applies) - it applies to email notifications and mailing list notifications.
May your sendgrid bills be cheaper…