There actually is an example in the README. However, since the library itself doesn't yet do a lot, the example is small.

Thanks for the link to SubEthaSMTP. Custom sender, recipient and message handlers are definitely on the roadmap. Connection limits and configuration of "all the things" are too, but I'm not too sure how to implement them yet. I'll have a look at SubEthaSMTP's source to see how it's done there.