Ars Dictaminis
The body is where you might give flattery and then make a request. Yup...sweet talking still works.
The principles set forth in Ars Dictaminis are still in use today. Although they have been revised and updated with the times, there are still strict guidelines to composing a letter today, which are not all that different from their roots.
Modern Usage of the Art of
Letter Writing
Even when writing emails, if you are writing to someone whom you respect (or at least should), then you would probably begin with salutations, such as Dear Elizabeth, etc, etc, etc. What a nice thing to say, my dear! At the end you probably write something like: Kind regards, Blah blahson
You are and probably always have been using stuff from ars dictaminis without even realizing it.
Here's a diagram of how to write a modern formal letter: