What if it does not go through?
Undelivered emails may happen when there are some problems with the internet connection. In that case every user ideally is supposed to receive the return email with the information that the message send out has not been delivered. Those pieces of information can be of extreme value to all people that were sending some important messages, that cannot be allowed to get lost on the way to the recipient. Undelivered emails are to be reported to the sender if those were send in form of bulk messages. It is also a sort of indicator of a effectiveness of a campaign. It is an indicator when the emails has been send over in large numbers of copies. Because in all statistical data everything that has any influence there has to be included in the calculations. Undelivered emails rate may not be that big but it might be important to consider for predicting the final rate. To get reliable data they have to as accurate as possible, otherwise the error in measurements will be too big for it to be used in further calculations.
