The first MIME email attachment was sent in 1992. On March 11, 1992, Nathaniel Borenstein sent a test message from Bellcore containing a photograph and an audio recording. The recipients included members of the emerging Internet email community, and the message demonstrated that different kinds of media could travel together in a standardized email format.
Borenstein developed MIME with Ned Freed to extend traditional email beyond plain US-ASCII text. MIME could label content types, combine multiple parts in one message, and encode binary data so older mail systems could transport it safely. The famous test message included a photograph of Borenstein’s barbershop quartet, the Telephone Chords, plus a recording of the group singing “Let Me Call You Sweetheart.”
A common mix-up is confusing the first MIME attachment with the first file ever sent by email. Earlier proprietary systems supported file transfers or attachments, including uuencode-based methods, but compatibility was limited. MIME made attachments broadly interoperable. The initial MIME specification was published as RFC 1341 in 1992; the later MIME standards were reorganized into the RFC 2045–2049 series.