It is possible to send emails to the courses members directly from eXact LCMS. In order to do so, please access the course of interest (Courses management > Specific Course) and click on the "Staff" link from the left hand side menu.
The "Course staff" window will then display:
Select the wished members by checking the boxes next to their names and then click on the "Send email to members" link from the bottom of the window. An email will automatically open up with the addresses of the selected members and the name of the course as subject.