Triggering an action when a package is available in the portal manager?

Hi all,

I was wondering what's the best (ie. clean & simple) way to trigger an action when a package is available on a computer, in the portal manager?

I would like to send an email to the user, documenting the whole process, but I don't want it sent before the package appears in the portal manager.

Is there any client-side check I could use, apart from the presence of the .xml file in the %AppData%\Local\LANDesk\Policies folder? Something server-side?

Or maybe another workflow/agent settings/distribution method? I'm using LDMS 2016.3.

The script itself is not a problem, I'm just searching for a reliable flag to use.

Thanks!