Previously the only email that could be used directly from within the Event Detail screen was the confirmation email, which, when set by the user, was destined to be sent a chosen number of minutes, hours, or days prior to an upcoming event. But there are of course many cases where one wants to send a confirmation right away (for example after having just discussed the appointment with the client), and of course there are other situations where one wants to send, from within Event Detail, emails other than confirmations.
At the bottom of the screen there is a drop down which allows users to choose the type of email to be sent. Next to that is the Send button. By choosing the type of email in the drop down and clicking Send, the user is then shown the email they are going to send, having a chance to edit it before finally sending.