Possible Clues:

• No private correspondence to begin: 'Old Impeder'
• Public communication welcoming landlord?
• Means of public protest
• Old writer, maybe I will offer communication for wide readership
• MLK wrote one in a Birmingham jail
• Communication intended for public reading
• Piece of "mail" meant for all to read
• Exposed, landlord in communication intended for publication
• Zola’s “J’accuse...!” for one
• Written missive intended for general consumption