I think if CC.com is like most other PHP based forums its automatic. You register on the website, include a valid email address and submit the registration page/form. An automatic email is then sent to the email address the requestor specified with a special link. Once clicked, it activates the account. This reduces the possiblity of robot accounts being created for spamming or other activities.
I could be wrong but I really doubt our mods have time to screen requests and launch the emails manually. I would sooner believe that MSN is trapping the activation emails and is misidentifying them as spam or containing malicious content.
