What to do with the interpolated letters

When we reach the letters quoted in text, code as follows:

<milestone unit="writtenText" resp="#Darioleta" ana="start"/>-->Este es <persName>Amadís Sin Tiempo</persName> hijo de rey - <!--<milestone unit="writtenText" ana="end"/>-->:</cl>

ebb: Wait a minute: Do these letters have recognizable headings, like "Dear Amadis," and closers like, "Sincerely"? Do they appear to be signed, like: Sincerely, Oriana?

If we are seeing some formal parts of a letter, I wonder if we should use a few elements from the TEI for correspondence to set these apart. If we are NOT seeing those, and just getting the body of a letter embedded in the main text, the milestone element as you describe makes sense!