X.400

(messaging)The set of ITU-T communications standardscovering electronic mail services provided by data networks.X.400 was widely used in Europe and Canada.

X.400 addresses tend to be much longer than RFC 822 ones.They consist of a set of bindings for country (c),administrative domain (a), primary management domain (p),surname (s), given name (g).

For example, the X.400 address,

c=gb;a=attmail;p=Universal Export;s=Bond;g=James;

might be equivalent to RFC 822

James.Bond@UniversalExport.co.uk

X.400

An OSI and ITU standard messaging protocol. It is an application layer protocol (layer 7 in the OSI model). X.400 has been defined to run over various network transports including Ethernet, X.25, TCP/IP and dial-up lines. See messaging protocol, XAPIA and CMC. Following is the format of an X.400 address:

/c= /admd= /prmd= /o= /s= /g=X.400Code Purpose /c= country /admd= administrative management domain (public email service) /prmd= private management domain (inhouse email) /o= organization /s= surname /g= given name