Joseph Habersham was Postmaster General between 1795 and 1801, serving under Washington, Adams, and briefly under Thomas Jefferson.
Here is a postmaster commission document issued by him dated February 24, 1800. It appoints William Kilby as the postmaster of newly established post office of Denneysville, Maine.
Josephine Clay Habersham was a granddaughter of James Habersham, who was an older brother of Joseph Habersham, the Postmaster General. Although her maiden name was Habersham, she married William Neyle Habersahm in 1840, who was a son of Joseph Habersham, thus a distant cousin. William died in 1864 during the Battle of Atlanta.
This genealogy derived from the Find-A-Grave website, a useful resource for locating relatives. https://www.findagrave.com/memorial...ay-habersham