OpManager's alert notifications gives you a comprehensive view of all the alerts that have been triggered in your network. Go to the Alarms tab where you will have a list of all the OpManager alarms. From here, you can perform a variety of alarm operations such as acknowledge, clear, delete, and etc. Here's the list of all the actions that can be performed from the OpManager's alarm tab.
When you configure for adaptive thresholds, OpManager will devise threshold values for monitors based on previous statistical data and will an raise alarm when a threshold is violated. Sometimes, the threshold value devised for a monitor maybe less than the regular usage value (which is considered safe for that device), so an alarm in that case does not indicate a serious problem.
For example, the threshold value for CPU utilization of an important application server that runs 24/7 maybe 30% during mid night but actually the usage may go up till 50-60%, which is considered normal because there are always users who access that application. So, an alarm raised for this device does not indicate a potential problem. You can mark such alarms as false using the 'Mark as false alarm' button.