  microsoft exchange server is calendaring software, a mail server and contact manager developed by microsoft. it is a server program that runs on windows server and is part of the microsoft servers line of products. windows messaging, initially also called microsoft exchange, is an e-mail client that was included with windows 95 (beginning with osr2), 98 and windows nt 4.0. ==history== planning the migration from microsoft's internal "legacy xenix-based messaging system" to the exchange server environment began in april 1993, and the process was completed in the late 1996 when the last xenix server on the ms corporate backbone had been removed. ===exchange server 4.0=== microsoft began a preliminary planning of the exchange 4.0 migration in april 1993. in january 1995, 500 users were running on exchange beta 1, 5,000+ users running on exchange beta 2a in september 1995, and finally all 32,000 microsoft mailboxes successfully migrated to exchange and microsoft exchange shipped in april 1996. microsoft it group actually migrated all microsoft employees to the exchange platform before the product had the official release status. it was the original version of exchange server sold to the public, positioned as an upgrade to microsoft mail 3.5. the original version of microsoft mail (written by microsoft) had been replaced, several weeks after lotus acquired cc:mail, by a package called network courier, acquired during the purchase of consumer software inc. in april 1991. exchange server was however an entirely new x.400-based clientâserver mail system with a single database store that also supported x.500 directory services. the directory used by exchange server eventually became microsoft's active directory service, an ldap-compliant directory server. active directory was integrated into windows 2000 as the foundation of windows server domains. ===exchange server 5.0=== introduced the new exchange administrator console, as well as opening up "integrated" access to smtp-based n
1996_software Groupware Message_transfer_agents Microsoft_email_software Windows_Server_System