TrackGpo_Smtp is a companion module to TrackGpo that enables you to receive SMTP messages when any GPO is added/changed/removed in your domain. You only need to run New-TrackGpoSmtpConfig in your session before running Invoke-GpoTracking to be good to go!

TrackGpo_Builtin is a companion module to TrackGpo that showcases how you can provide the external functions for use with TrackGpo