The ISODE Consortium MTA is a high-performance, high-capability multi-protocol message transfer agent. It implements both the X.400/MHS 1988 and SMTP standards for messaging including their related content-types and addressing. It supports sophisticated and extensible content and body-part-type conversion capabilities. This provides the capability to gateway between different types of mail system, in particular between X.400 and Internet mail.
X.400 Conformance
The capabilities of the MTA are based on the service elements and protocols defined by the MHS (MOTIS) series of standards [X.400, ISO/IEC 10021] for the Message Transfer Service. All the Basic Services are supported. All the Essential Optional User Facilities are supported. All the Additional Optional User Facilities are supported with the exception of deferred delivery cancellation and explicit conversion.
Functional Groups
The following functional groups are supported:
Conversion (CV)
Distribution List (DL)
Redirection (RED)
Latest Delivery (LD)
Return of Contents (RoC)
Use of Directory (DIR) (excluding use of Directory Name when
O/R Address does not identify a user and use of Directory to determine a recipient's capabilities),
1984 Interworking (84IW) (excluding internal trace information).
The Physical Delivery (PD) and Security (SEC) functional groups are not supported.
Queue Manager
The operation of an MTA is based around a queue. The queue is managed by a Queue Manager process (qmgr) which invokes various so-called channels to process messages. Processing can include conversion when necessary but mostly involves relaying messages to the next MTA along their route or performing final delivery for local users.
Security
In IC R3, the message security element type definitions have been aligned with the most recent X.400 specifications.