Hi,
At the moment plugins can be used in two separate ways:
1. As an event listeners.
2. As producers and handlers of routes.
If you're talking about the first way, then I really don't think that you could easily add emails sending. You see, plugins in Mibew do not get an instance of \Mibew\Mail\MailerFactoryInterface
that is used to send messages in controllers. (It seems to be an architecture flaw but I don't see a simple way to fix it.) At the same time, you could create an instance of this class by yourself in the plugin.
If you're talking about the second way, you could just use $this->sendMail(...)
in your controllers.