Knock three times
A notification email works like an alert to someone when something has been done. The next time you have implemented a notification email to your system, you’d probably want to read this:
1) For important action only such as payment received, renewal reminder, etc
2) Keep it short. Since this is repetitive, readers will take snap than reading through
3) If the occurrence of an action is high in a day, consider stop sending notification
4) Send out from noreply@xxxx.com. You don’t expect replies anyhow.
5) For extremely urgent case, add SMS features. After all, it is about alert.