For certain repositories it's also useful to install a git hook to prevent individuals from pushing without properly configuring name/email in .gitconfig. This assumes you have administrative access to the server, of course.
wait, isn't it one of core purpose of VCS like Git to know who is doing commit ?
I mean how can you not know who did commit ?
You can also add ".patch" at the end of a github commit url, which will show the users email address. For example:
https://github.com/TinyCC/TinyCC/commit/c52d79605a3c895a16e1...