No more correspondence; the formal conclusion is a relationship ended by written declaration. Lawyers apply it to wrap up cases. Ex-lovers utilize it to draw borders. Emails, letters, texts, reconciliation efforts no more. The door is sealed, not just closed; it's also sealed with correspondence showing formal contact between people who once something more personal.
No further letters is more conclusive than let's take a break but more elegant than ghosting. It is divorce without marriage, severance without a job, the professional manner to say you're dead to me.
Certain relationships, toxic friendships, scheming exes, con artists pretending relationship, merit this clarity. Clean breaks repair more rapidly than vague fade-outs. It is terrible, though, this formal rejection, corporate jargon used on human relationships. No further letters imply: cease hoping, cease striving, stop living in my inbox.