Notification system

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Can you guys recommend a good notification system for our internal users?

I am looking at setting up notifications in cases like when we have issues with email, we can send a notification to the user that will pop up letting them know that the IT department is aware of the issue and is working on getting it fixed, etc..

I was looking at doing this with SCCM using something like a custom hta but it's not instantaneous and doesn't seem to fit the requirement.