Go to My Account > General Information, and underneath the box in which your email address is in, there are two options:
* Receive NG news updates?
* Receive daily Flash Portal Top 5 notices?
Make sure the box you want is ticked. If it is and you're still not getting the emails, then it's probably a problem with the mailing list.
You don't by any chance have AOL, do you? I think a while back, there was something that went wrong if you used AOL, like an automatic junk filter or something that prevented the emails being sent to any of the AOL addresses. More info on that here, if it applies to you.