Sexton maintained a busy schedule, but found time to keep up active correspondence with many friends and colleagues, in addition to being very conscientious about answering fan letters and inquiries about readings and performances. Sexton kept carbon copies of almost every letter she wrote. As a result, the correspondence series has a very high match rate between letters received and letters sent out. This series is fairly evenly split between business and personal correspondence and includes communication with universities, libraries and other organizations as well as individuals. Of particular note is a great deal of correspondence with Alice Smith, a woman she had met at a reading in New York in 1967 and with whom she exchanged letters until her death. An Index of Correspondents is located at the end of this guide

Over 800 letters written to Sexton by fans are located in the Miscellaneous series under the heading "fan mail," and are organized chronologically. 409 letters written by Sexton to fans and other correspondents are found in the Miscellaneous series under the heading "Letters to correspondents." Additionally, correspondence between Sexton and many of her students is located in Miscellaneous series. These letters are not included in the Index of Correspondents.