I have heard from a couple of people that they got an email from the Class Creator website telling them they should "whitelist" the following email address:  noreply@classcreator.net

Evidently that sender address might get identified as spam by some filtering programs.  To keep any website generated emails from going to the Spam folder, I believe you need to enter noreply@classcreator.net into your contacts (address) list. 

I have not done that, and have not missed any emails, so I guess my Spam filter isn't as comprehensive as some, although I never (boy, I hate to say that out loud) get Spam emails.