Gmail (and other email clients) will group emails from the same sender with the same subject. If you are using Gmail and receive regular notifications from a form, you may run the risk of missing an important notification because it is lost in a very large group of all of the notifications from the same form with the same subject.
A solution to the problem is dynamic population the subject of your notifications based on a condition. I think the easiest way to accomplish this is to insert a field in the subject line. That field could be any field in your form (including hidden fields)and you could set it with any value you choose based on whatever conditions you want.
Another solution is changing your settings in your Gmail account. If you are receiving a lot of notification email from the same sender wit the same subject, Gmail’s grouping makes it difficult to sort them daily. Turn of Conversation view in Gmail. It is easy, and saves a lot of confusion. In Your Gmail account go to Settings. Scroll down to Conversation view, and click the “Off” radio button.