Rec. ITU-T F.420 (11/1988)  – MESSAGE HANDLING SERVICES: THE PUBLIC INTERPERSONAL MESSAGING SERVICE
CONTENTS
1 Purpose and scope
    1.1 General
    1.2 Message handling systems used in the provision of IPM service
2 IPM service
    2.1 General service requirements
    2.2 IPM service features
    2.3 Responsibility boundaries
    2.4 Message store
    2.5 Use of directory
    2.6 Security
    2.7 Distribution lists
    2.8 Intercommunication with physical delivery services
3 Types of body parts
4 Conversion between different encoded information types
5 Naming and addressing in general
    5.1 Directory names
    5.2 O/R names
    5.3 O/R addresses
6 Operation of the service
    6.1 General
    6.2 Message handling phases
7 Quality of service
    7.1 Message status
    7.2 Support by Administrations
    7.3 Model of delivery and notification times (see Figure 1/F.420)
    7.4 Message delivery time targets
    7.5 Delivery notification time targets
    7.6 Receipt notifications and non-receipt notifications
    7.7 Error protection
    7.8 Availability of service
    7.9 Minimum storage capacity
8 Tariff and accounting principles
9 Network requirements
10 User information and support
11 Use of the IPM service within CCITT-defined telematic services
ANNEX A – Abbreviations
ANNEX B – Subscriber access and terminal requirements
ANNEX C – IPM service elements from 1984 X.400 Recommendations