A fully qualified domain address (FQDA) is a string forming an Internet e-mail address. It was defined by the Internet Engineering Task Force in RFC 3801 for the use in voice profiles for Internet mail,RFC 3801, Voice Profile for Internet Mail - version 2 (VPIMv2), G. Vaudreuil, G. Parsons (June 2004) but has been used on the Internet as early as 1988.
