Electronic mail was first used between users on the same mainframe computer in 1965 and allowed communication between compatible systems starting in 1966. The first email sent between different computer networks was over ARPANET in 1969. Standards for email addressing and transmission were established in the 1980s, allowing proprietary email applications to develop for personal computers and local area networks. Attachments and HTML were added in the mid-1990s through MIME standards. Email standards have continued to be updated, and email data has been used as evidence in litigation and should be treated as an official record. Effective electronic records management systems are needed to adequately archive email communications.