Please create a documentation guide for this project

If the maintainer would create a documentation guide, then the community could contribute pages to explain these things. @MrPhilbert, I assume you would write up and contribute what you have learned so far, if there was a place to put that information? Then others could improve what you started.

Good documentation needs:
1) A place to put the documentation
2) A community willing to contribute by writing new documentation / editing existing documentation

Only the project maintainer can create a documentation guide for this project. To do so, edit the project page, scroll down and select the "Project documentation" vertical tab, then click on "Create a new Drupal 8 documentation guide". Save. Then the new guide will show up on the project page and the community can contribute.

Now that I have been given maintainer privileges, I was able to create this guide and migrate the old documentation pages into the guide.

See https://www.drupal.org/docs/7/modules/mime-mail

Note, ANYONE in the community may modify or add to this guide, so if you think something needs documenting, or if you think the documentation is wrong, or if you have experience using Mime Mail and have something to contribute, PLEASE ADD TO / EDIT THE DOCUMENTATION!

But, why was the documentation guide made in the Drupal 7 section?

The guide was made by migrating the existing non-guide documentation into a documentation guide. The existing documentation was for D7. There is no existing D8 documentation yet. I don't know why I didn't create an empty D8 guide at the same time, but I just did that now: https://www.drupal.org/docs/8/modules/mime-mail

If you want to help out you can start creating pages in the D8 guide. I suggest copying the D7 guide's structure, and copying the content too IF that content still applies to D8.

Awesome, thanks. I'll see what I can do for documentation, but no guarantees. First up will be an attempt at porting the format module, since we'll need that for Gmail support. :)