As I write this, Microsoft Exchange is nearly eight years old. On June 11, 1996, Microsoft released Exchange Server 4.0, the successor to Microsoft Mail. This represented the beginning of a new era of client/server messaging for business users. Unlike Microsoft Mail, which used a post office–style e-mail system with a shared file system, Exchange provided a server-based message store for users.
Almost a year later, in March 1997, Microsoft released version 5.0 of Exchange Server. This new version represented a significant improvement over the prior version, mainly due to the addition and integration of Internet-based protocols into the product, such as:
Lightweight Directory Access Protocol (LDAP)