Just go to lower right of the interface and click on the up ^ arrow next to your location. You will see three available options on Status:
- I am available
- I am busy
- Hubgets knows better
If you pick "I am busy" you will never get those notifications - this is a little bit extreme, but considering that you can change the option anytime it's ok. A better option is maybe "Hubgets knows better". In that case you will let Hubgets decide to push or not notifications to you based on an algorithm.