You asked another question, which was whether you could exclude specific forums from the email digest type.
Yes, you can
Go to yourmoodle/mod/forum/index.php?id=1, which will show all the forums on the site front page. For forums in specific courses, change the id=1 to the number of the course - you can see that when you go into a course - eg, yourmoodle/course/view.php?id=3
Note - unfortunately, you cannot see all forums across your whole site on one page - you have to view this page in each course
I actually put a link in each forum so that people can change their email subscription preferences at any point...
