I like how easy it was to setup, configure & test my email using the online GUI tool with no hassle at all! There's nothing really that i dislike about this app so far when compared against other similar apps out there (like Postmark). You can send emails from your own domain or use third party services such as gmail etc without any issues in terms of sending large volume mails through our service provider hosted servers/platforms as well. We're able handle over 10k messages per day while maintaining SLA compliance standards which are difficult if not impossible otherwise via traditional methods especially given we have thousands + users who rely heavily upon us daily! No complaints yet but would be happy hearing more feedback should you find something worth mentioning - either negative comments regarding functionality improvements OR positive ones related specifically around pricing / package costs vs usage limits.