Exactly what I wanted. Rated 5 out of 5 stars
I've been searching all over for a tool that would backup all my email in a way that was quick and simple. I'm glad to have found that tool.
Some others (including the default Thunderbird) would back them up but the file encoding would be off (Korean characters in particular would be either hex codes or question marks) or use an unhelpful format. Most all were rather complicated.
Not only was this easy to use, but it provided all the options I could have hoped for and then some.