This figure displays logical components for identity-based communications scenario 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 Portal Server and Communications Express logical components.
The next tier to the right, the Business Service Tier, contains Messenger Server MMP, Messaging Server MTA, and Access Manager logical components.
The rightmost tier, the Data Tier, shows a Messaging Server STR logical component with storage, a Calendar SErver Back-end component with storage, and a Directory Service logical component with LDAP storage.