On my home laptop I use git for personal projects and company projects, when using git I try to use the appropriate email address for task. 
On a project I was working on today I managed to forget to do this and made 20 commits in the wrong email address. Git is an incredibly versitile tool and I frequently find i’m restricted not by what it can do, but my knowledge of the tool which will help me! In this case it was git-filter-branch, which lets you rewrite history, in seconds.
I used the following to rewrite my email address from work to my personal email address
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Edit:I forgot about the git committer field though, doh!
 Easily achieved by setting my work email in the global .gitconfig and per-repoistory config overrides for exceptions on personal projects (in the minority)