From Georgetown University Commons Knowledge Base
You've likely noticed that the Settings >> Discussion options include "Email me whenever anyone posts a comment." This is a default option in the Wordpress system, but has been turned off for Georgetown Commons blogs. Even if the boxes are checked, you will not receive any email notifications.
This is part of the way the system is configured to fight against spam-related email. We are always working with the Security office to improve/protect against spam, but it is an on-going battle.
If comments are an essential element to your class blog assignment, try these work-arounds:
Have your students use the Email Users plugin and then send an email to you letting you know that they have made a comment.
Turn on comment moderation. From the Dashboard, go to Settings >> Discussion, and find the option "Before a comment appears," and check the box next to "Comment must be manually approved." This will require an administrator to approve comments before they are publicly posted to the site, which automatically notifies the administrator. The drawback of this method is that students will not see comments immediately, which may delay discussions or responses.