The most available and easiest form of interactvity on Senator Boxer’s page is clicking through links to her biography, lists of services her office provides, issues she is involved with, etc. The discussion is laid out for you.
As readers read left to right, I would say that Senator Boxer’s page puts user participation at a low priority as “Contact” is the right most tab. It is unfair to say that Senator Boxer is unavailable, as many of the links (toward the left) lead one to a phone number or email address. However, these means of connection are private and not visible to other users.
Boxer does provide an option under “Press” (the second right most tab) to subscribe for updates. She also makes use of social media by providing a link to her YouTube channel and flickr photostream.
If you want to make a comment, you must chose from under 50 topics (though this is a large number it seems limiting compared to when we can write about whatever we want on Twitter and YouTube). And again, OTHER USERS DON’T SEE YOUR COMMENTS. The only UGC visible is the comments posted on YouTube videos (and, when you chose a topic to submit, you can chose from the “most popular topics this month” or scroll down. a very abbreviated view of public concerns). You must leave Senator Boxer’s website (and go to YouTube or Flickr) to see any public comments.