I have chosen to subscribe to all of my classmates' profiles (because I am the website administrator). According to the site, I should be receiving emails each time a profile is updated. We have had people update their profiles, but I don't get an email notification that this has taken place.

Two things you should know:

1) Profile Update emails are only sent once per day. So if somebody just updated his or her Profile, you should not be expecting to receive an immediate email. There's a good reason for this that's usually not apparent to people. And that reason is that Classmate will edit their Profile, check it out live, go back in and make some more edits, check it out live again, etc. In the process of updating a Profile the Profile can get saved numerous times. If we sent out a Profile update email each time that happened we'd drive people crazy. So instead, in the morning our system scans the entire user base for update Profiles, and then delivers Profile update emails to subscribing members.

2) If you're not getting Profile Upate emails after 24 hours of the update, then you have an email problem. The emails are being sent. Have you checked your spam or junk email folder in case they went there? Have you whitelisted the email address postmaster@classcreator.net? Does your email provider have any higher level spam filtering in place before your own spam filtering happens?

I get other emails from the site - like the mass emails that I send to the class, and when others send me messages through it. I'm just not getting the profile updates at all.

Could it be that I notice someone has updated their profile when I am in the site (less than 24 hours since they did it), and I check out their profile then?

Yes you could be seeing their update on the site and then not receiving the notice until the daily notices go out that night.