[Evolution] Question about accounts

[Bart <montana_evolution_user hardinmt us>]

In my copy of evolution, (3.10.2), there is an account named "On This
Computer" of type Maildir.

I didn't create it, and I can't edit it, or see any settings or the
like.  It wasn't there, at least I couldn't see it, in earlier versions
of evolution.

Why is it there?  What's it do?  Doesn't seem to affect my use, I'm just
curious about it.

Bart