If you have an open source project used by more than yourself, please don't make yourself uncontactable. If you've abandoned the project, make it clear that you have and if you're lucky enough to have an active fork, point to that.
This isn't about contacting people or communicating the status of a Github project. Github issues are fine way to communicate. If the repo owner isn't responding to issues, I don't think sending email to someone's personal email found through GIT commits is a good option. There is a reason we don't just have everyone's personal email on their Github profile. People don't want spam from people they don't know.
