One of the most important applications of a directory is storing email addresses and other contact information. Although many ad hoc solutions to this problem have been implemented over the years, LDAP provides a natural online publishing service for this type of data. This chapter explores the ins and outs of integrating email clients (MUAs) and mail servers (MTAs) with an LDAP directory. It covers the configuration details of some of the more popular email clients, including Mozilla Mail, Pine, Microsoft Outlook, and Eudora. We'll also discuss the schema required to support these clients and the types of LDAP searches to expect when the application attempts to locate a user in the directory.
On the server side, we'll discuss three popular email servers?Sendmail, Postfix, and Exim?all of which can use a directory. We will cover the level of LDAP support within each MTA, the schema needed to support this integration, and the configuration process for integrating an LDAP directory into a production email environment. This discussion assumes that you are familiar with basic MTA administration and the interaction between SMTP servers.