There are a lot of topics and forums on the Rackspace Community. To make sure you are notified you can email subscribe several different ways to groups, forums, or specific topics. Remember you can configure your overall email preferences in the email tab under settings.
To subscribe to a forum, select the forum you wish to watch and click on "Managed Subscriptions" on the right hand column under "Options".
Here you can view all the forums which you are subscribed to in the group and make changes at the group level.
You can subscribe to digests if you don't want to receive all the notifications but really just want a summary of the hot topics of the group. To subscribe, go into your profile and click on the "Email" tab. Select the frequency of daily or weekly digests.