postletter

Postletter is a cross-domain term used to denote a supplementary element attached to a letter or letter-like document. The precise meaning varies by field, but in general a postletter serves to update, explain, or extend the original communication after it has been issued.

In epistolary practice and archival contexts, a postletter is a note added after a letter has been written to supply corrections, clarifications, translations, or additional context. It may be authored by the original writer at a later date or by a recipient who wishes to annotate the correspondence. In manuscript studies and library archives, postletters can document revisions, provenance notes, or cross-references to related documents, aiding researchers in understanding the full communicative chain.

In publishing and literary collections, postletters appear as supplementary material accompanying collections of correspondence. They may record editorial commentary, reader responses, or situational notes that illuminate the circumstances surrounding the exchange.

In digital communications, the term is used informally to describe follow-up messages that refer to earlier content and thereby extend the thread. This modern usage overlaps with familiar concepts such as a postscript (PS) or a reply in a conversation, but postletter emphasizes the additive and communicative nature of the follow-up.

Overall, postletters function as ancillary materials that preserve context, correct or augment information, and connect related correspondence. They are not standardized and their form and authority depend on the practices of the field or institution involved. See also postscript, addendum, appendix.