Users should have the ability to Delete & Add the ENROLMENT MESSAGE and the EXCEPTION REPORT MESSAGE within a Program. These emails are sent instantly so there is very little flexibility in the order with which a Program is setup. e.g. if Program Assignments are defined before Messages (as the order of these tabs implies, from left-to-right), then users will be sent a potentially undesired "Welcome" email! Plus, the email is only in PLAIN TEXT (confirmed by Yuliya here: https://totara.community/mod/forum/discuss.php?d=17565), which is also quite restricting.
Our requirements were to enrol an Audience of users on a Program with a few required courses, and accompany this with a fancy "Welcome to the program..." email that includes our corporate font and colours, and a hyperlink direct to the learning dashboard page. The closest we can get, instead, is sending the [duplicated!] "You have been enrolled..." PLAIN TEXT email from Totara, then email our fancy email supplement, which is just not desirable.