Three-Tier Client-Server Arch.
Client computer with Web Browser
Server computer with Web server software
Server computer with email server software
performs the same functions as the mail server in the two-tier example
sends HTTP requests to the Web server
- sends HTTP responses to the Web client
- translates the client’s HTTP requests into SMTP packets then send them to the Mail server
Best known example: Web based email (e.g., Hotmail)
No need for an email user agent