Platform SDK: CDO 1.2.1

Comparison of CDO Libraries

The CDO Library and the CDO Rendering Library are often used in conjunction with each other to accomplish a wide variety of tasks. The CDO for NTS Library is intended as a streamlined alternative for a frequently used subset of these tasks. It operates independently of the other two libraries.

All three CDO libraries have features useful to applications in different circumstances. The following table compares the features of the CDO for NTS Library with those of the CDO Library used with the CDO Rendering Library:

Feature	CDO for NTS Library	CDO and CDO Rendering Libraries
Based on MAPI	No	YES
Supports profiles	No	YES
Supports authenticated users	No	YES
Supports address book access	No	YES
Supports remote server access	No	YES
Supports SMTP access	YES	No
Supports calendar access	No	YES
Supports HTML rendering	No	YES
Supports MHTML messages	YES	No
Supports NewMail object	YES	No
Can be called from ASP	YES	YES
Compatible with IIS 4.0 and MCIS	YES	No
Compatible with Active Messaging 1.1 applications	(partially)	YES

The CDO for NTS Library is functionally compatible with a subset of the CDO Library version 1.2.1, and with a subset of the Active Messaging Library version 1.1. If an application has been written for either of these libraries, some modifications are usually required to run it with CDO for NTS. Some features of Active Messaging, such as fields, folders, and address lists, are unavailable in CDO for NTS.

A developer may be uncertain whether to use CDO for NTS or the CDO and CDO Rendering libraries. You should use CDO for NTS if you

require support for MHTML;
anticipate heavy automated generation of outgoing e-mail;
intend to send unauthenticated e-mail from Web sites;
use server-based replication of messages;
anticipate using e-mail for server-based notifications.

You should use the CDO Library in conjunction with the CDO Rendering Library if you

require authenticated user support;
need to render objects or data into HTML;
need to access a personal calendar store;
intend to access multiple remote Microsoft® Exchange Servers;
anticipate accessing e-mail from remote sites;
use server-based custom mail agents;
require automatic load balancing of outgoing mail;
are primarily upgrading an existing CDO 1.2.1 or Active Messaging 1.1 application;
are developing a client application;
need to filter or sort messages;
require support for multiple address book and message store providers;
are developing a three-tier Web-based e-mail application.

You can use either CDO for NTS or the CDO and CDO Rendering libraries if you

are developing a server application;
intend to use server-based custom e-mail agents.