This is how I explained it elswhere on a forum by groupee:
Our message boards have a new feature called the “Ignore List.” Use this feature to avoid seeing the posts of any user(s) you choose to ignore. For ignored users, replies in topics are hidden by default. In addition, you will not receive notifications of new content by ignored users and ignored users will not be able to start a Private Message with you.
How to use the Ignore List
1. Write down the display name of the user(s) you wish to ignore.
2. Select “MY PROFILE” from the top navigation panel.
3. Select “Ignore List” from the left menu options. This will open up your Ignore List window.
4. To add someone to the list, click the “Add Users” link (near the top of the window). A pop up window will appear.
5. Type in the Display Name you wish to ignore and click on search. You will then get a list of names that closely resemble what you have typed in.
6. Put a check in the box next to the name you wish to ignore and click on “add selected members”.
Another way to ignore a Display Name can be done right from a discussion. You start by clicking on the name you wish to ignore. A drop down menu will appear. Click on the option second from the top that reads, “add ‘name’ to my Ignore List”.
What you will see for ignored users
You will still be able to see their post if that user starts a new conversation.
For every post by an ignored user in which he/she is contributing to an existing conversation, you will now see a one line comment indicating there was a post, accompanied by the date and time of posting. If you wish, you can view each post by clicking the “”Show Post” link.