Labels:text | diagram | screenshot | number | line | rectangle | font | plan OCR: X.400 MODEL P2 User Agent Virtual Connection P3 (P2) P3 (P2) User Message Transfert P1 IMTA Agent IMTA) Other E-mail Message PE System Transfer System P3 P2) MTA PI (P2) Message Access Unit Store IMSI PI (P2) PZ (82) User Gateway Other E-mail System FIGURE 3: A user gains access to an X.400 mail system via the User Agent, which is responsible for helping users compose, send, and receive mail. The Message Transfer System, which delivers the mail, is made up of Message Transfer Agents (MTAs) and Message Stores (MSs). Access Units (AUs) are gateways to systems such as fax or Telex.
