How to we stop GitHub from emailing too many people too much

I recently joined a research team that uses R and Git/GitHub. The team includes 4 full-time R programmers and 10 social scientists who only run simple analyses.

I was told by one of the more experienced programmers on the project that they haven't found a way to use many of GitHub's tools for collaboration (bug reports, to-do lists, code comments, etc.) because they generate emails to everyone who is a contributor to the repo every time.

This is incredibly puzzling to me, so I'd love to hear from someone that there are ways to adjust the email settings. I'd expect there would be multiple ways, so that individuals could opt-in or opt-out of certain emails, and also so contributors could explicitly choose whether certain people get certain emails or not.

Is it possible to adjust these settings?