I use gmail, and I actually didn't receive a notification from a school. They swore they sent it out, but I never received it. I am like all you other SDNers out there and check my email (including spam) every five minutes or so (ok, a little exaggerated, but I check frequently). I called them and they resent it and I got it without a problem.
However, I DO NOT BLAME GMAIL. I believe the problem is either a user error on the part of the school or their email service not working correctly.
I mean let's be honest. Most of these emails are sent out by a middle to older-aged lady who could easily have made an error. Some email services even limit the number of recipients for any given email, so even though they might have intended to send an email to 400 people, it may have actually only gone to 300...
So I am not saying that it is DEFINITELY a user error, nor a problem with the service, I am just saying that I believe these scenarios to be more likely than there being an inherent problem with gmail. I bet that a large portion, if not the majority, of applicants use gmail and have had no problem.
So if you are really nervous about it call the schools (like I did) and they will tell you what your status is. Good Luck!