When a batch of emails are sent using the print management email method, it is not unusual for failures to occur, especially when using the Purpose placeholders.
It is near impossible to find out which email did not send.
It would be great to get a more detailed message so that users know exactly what customer/vendor (for example) the batch failed for.
It would also be good for the user to be able to see a log of each email that was sent. Even if it was logged to the Email sending status queue.