I just migrated from Mail Poet version 2 to version 3 and only did so because SendGrid is requiring it. Mail Poet version 2 is a lot more efficient and more streamlined with respect to sending newsletters. In version 2, the newsletter can be sent out with one click. Furthermore, the screen with newsletters (emails) in Version 3 is NOT as clean and user friendly as version 2. In Version 2, the templates were highlighted in light blue and allowed to easily distinguish between the templates and those sent.