Comment by the_why_of_y

That can't be the first one. Colin Powell used a personal email account during the GWB administration.

https://www.npr.org/2016/09/08/493133413/colin-powells-ways-...

Of course that pales in comparison with the practices of the GWB White House:

https://www.newsweek.com/2016/09/23/george-w-bush-white-hous...