The webmail server, also known as mshttpd (Messaging Server HTTP Daemon), provides email services to the Messenger Express and Communications Express clients. Now, the webmail server accesses the message store through the IMAP server. This provides several advantages:
Messenger Express and Communications Express clients are now able to access shared folders that are located on different back-end message stores.
The webmail server no longer must be installed on each back-end server.
The webmail server can serve as a front-end server performing the multiplexing capabilities previously performed by Messenger Express Multiplexor (MEM).
MEM is no longer used.
On the client side, nothing is changed except that users can now access shared folders that are not on their message store. In previous versions, the MEM received HTTP client requests and forwarded it to the appropriate webmail server on the appropriate back-end message store. Because of this, a copy of mshttpd had to be installed on every back-end server. Now, the webmail server operates as a front-end server receiving HTTP client email requests. It translates these requests to SMTP or IMAP calls and forwards the calls to either the MTA or the appropriate IMAP server on the back-end message store.