Multichannel Memorandum Distribution Facility. One of the two Mail Transfer Agents used on SCO OpenServer systems. The other is sendmail. MMDF provides transparent access to the different networks and mail transport protocols, regardless of the Mail User Agent employed (one or more MUAs may be used on a single system).
MMDF, the Multichannel Memorandum Distribution Facility, is a mail transfer agent (MTA), a computer program designed to transmit e-mail. It was originally developed at the University of Delaware in the late 1970s. It grew in popularity throughout the 1980s, and was selected by The Santa Cruz Operation as the MTA it would distribute with SCO UNIX in 1989.