GigSpace tells you about things that need you: offers, changes to a gig, check-in prompts, cover requests, and money.
You can control most of this in your notification settings. Each type can be set to arrive immediately, be gathered into a daily digest, or be muted.
Some things can't be muted. Check-in prompts and the day-of alert are always immediate, because they're the ones that stop a venue being left without an act. That's deliberate.
If you're getting more email than you want, move the noisier categories to a digest rather than muting them: you'll still see everything, just once a day.