Complete Protocol dictionary, glossary and reference
MHS: Message Handling Service
Message Handling Service, defined in ISO X.400 specifications, is for email transmission specified by the ITU-T and ISO. X.400 is common in Europe and Canada and is an alternative to the more popular email protocol, Simple Mail Transfer Protocol (SMTP), which is defined by IETF. X.400 uses a binary format so it is easy to include binary contents without encoding it for transfer. Also, it is harder for people to fake email addresses and contents than with SMTP, where text messages are used.