I have opted to be notified when my question is responded to even if not a full answer but I have received not such notification??
The email notifications per question were removed in the SE 2.0 engine - however they were replaced by getting all your notifications in a single email batched up at an interval of your preference. You can set this preference on every page! Here's how:
Click email settings in the Stack Exchange dropdown:
Then enter the email you want them sent to, and the interval you want (we only send if there was something, and you didn't already read your inbox on any site):
We will send you a one-time email verification (to prevent spamming random people - we make sure you asked for these emails) then you'll receive your inbox updates only if you missed anything. You can opt out of the emails at any time by changing the preference of via a one-click link in the footer of each email.