Uptime alerts notify you after an error has been detected, once the issue has been resolved and all of the tasks under the device are reporting a successful monitoring result again.
If you have created a device with two monitoring tasks to make sure that two web pages are loading, and the second task returns a 404 error, the entire device will be flagged as down.
The device will continue to be flagged as down as long as any of the underlying tasks are still returning an error (Unless you have applied a filter to the device that purposefully ignores specific errors).
if you have selected to send uptime alerts in the device configuration, once all of the tasks included in the device have EITHER returned a successful result OR you have applied a filter to the device that purposefully ignores the existing errors, an uptime alert will be generated.
Uptime Alerts can be enabled on the device level.
When an uptime alert is enabled on a device, an uptime alert is sent to the specified email addresses or alert groups when all detected errors have been resolved.
Uptime Alerts are only sent when all tasks in a device are functioning properly or you have applied a filter to the device that purposefully ignores specific errors. If you wish to receive uptime alerts for individual tasks, each task should be attached to a separate device.