I was wondering how this feature worked. The best place to start is “help” where it provides step-by-step instructions. Therefore, I looked it up under support and found this article Post by Email.
So, the cool part is that the article spells it all out. The subject line is the title and the body is your post. It also provides shortcodes to enter in the body and some are quite interesting. You should check out the support document.
I am going to test this graph to see if it works. Wish me luck