I eventually went with Active Module's Active Forums 3.6 for this installation. AF 3.6 allows you to subscribe to receive an email anytime there is a post in a forum (Email me when someone posts to this forum). The checkbox to turn on email notification is easy to see, at the top of each forum when you enter the fourm.

The DotNetNuke core Forum Module *also* allows you to subscribe to receive an email notice whenever there is a post in a particular forum. (My Settings > Tracking/Subscriptions > Tracking Forums). Active Forums has the setting easily visible, while DotNetNuke (4.3.6) has it tucked away under My Settings. Since the user base for this portal is not that tech savvy, I chose the easiest way for them to know/learn about getting an email when a post is made.

With all due respect, DotNetNuke's Forum Module has all the email notifications settings together in Tracking Forums, so it's easier to manage email notifications for ALL forums from one page.

Agree: with larger portals, 'Email All Users on Any Post' would be a huge burden on the system. And you cannot put in an option that works only for small installations. Thank you for giving me the conclusive answer.

Crispy: when in there making revisions to the Forum Module, would you please consider this one; it still causes me trouble. Thanks very much:

http://www.dotnetnuke.com/Community/ForumsDotNetNuke/tabid/795/forumid/8/threadid/54855/scope/posts/Default.aspx