This figure displays Messaging Server services in the Client Tier, Presentation Tier, Business Service Tier, and Data Tier of the Multitiered Architecture Model.
The leftmost tier, the Client Tier, contains representative email client applications and browser-based client applications.
The next tier to the right, the Presentation Tier, contains a Communications Express logical component.
The next tier to the right, the Business Service Tier, contains Messenger Server MMP and Messaging SErver MTA logical components.
The rightmost tier, the Data Tier, shows a Messaging Server STR logical component with storage and a Directory Service logical component with LDAP storage.