The incoming correspondence consists of letters of individuals and companies sent to John Murray, publishers, mostly relating to the business, but also including private letters. The correspondence largely covers the period from the 1760s to the 1920s. Where enclosures exist, they have been kept with their original letters.

This series contains most of the extant letters received by the publishing house up to the 1920s, but others are to be found throughout the archive. One significant sequence that is separate contains the correspondence and related papers, including some manuscripts, of many prominent authors (MSS.42000-42631).

Although there are occasional copies of outgoing correspondence within these folders, the majority are recorded in the copy letter books (MSS.41896-41999).