Letter-quality Definition

lĕtər-kwŏlĭ-tē
adjective
Of or producing printed characters similar in quality and clarity to typewritten characters.
Webster's New World
Good enough to be sent as a letter, a term used to describe the niceness of a printed text. Now somewhat obsolete due to advances in printer technology, a legacy of a time many printers offered a choice of faster draft-quality and a better appearing letter-quality.
Wiktionary