You will need to verify a few settings to make sure everything is setup correctly. First, make sure when you enabled Auto Notifications that you actually added a role to be used. You need to click the green plus icon next to the role you would like to receive the auto notifications. You can have more than one role setup for the auto notifications feature but you need to make sure they have been added properly. Next, go to the main settings page and see if the Mail Queue option is enabled. If the Mail Queue option is enabled you may need take a few extra steps to make sure the scheduled task is running properly. Follow the steps below to manually start the task:

1) Log into your portal using a Super User Account.
2) Select "Scheduler" from under the Host menu
3) Click the pencil icon next to the task named "Active.Modules.Forums.Queue.Scheduler, Active.Modules.Forums.40"
4) Make sure the checkbox next to "Enabled" is checked and click the "Update" link button.

Please contact support if you are not using the Mail Queue or have verified that the Mail Queue is working properly and have ensured that standard notifications are being sent properly