I have a client that finds the 'Send' button very intimidating. It suggests that pressing the button immediately sends the e-mail, while they're first selecting a segment and have an opportunity to view the segment memberlist. Maybe change it to something like: "Start Send Proces"?

You can probably think of something better, but I think my client had a good point about the button being worded in a way that makes it more scary to push than it has to be. Many of Dynamics 365 end users aren't very skilled with computersoftware. Little details like this matter.