Go to http://login.postini.com and entering your username and password.  Please be sure you are entering @firststepinternet.com for your Postini username. 

This will take you to your Postini Message center where you can modify your Postini Settings and see what messages the service has stopped.  To check your Filter settings or add some one to your blocked senders list:
Click on the "Junk Email” settings link.
In the “Sender Lists” section, under the "Blocked Senders" category, type the address of someone you never want to receive mail from in the field provided. Click the “Save to list” button and that sender will be blocked by the filter. You can then log out.