Physically consolidating IT assets makes it easier to administer and maintain them, requiring fewer IT administrators and lowering labor costs. As Sun Java System Communications Services software is highly scalable, only a handful of Sun servers are required for even the largest enterprise deployments. Perhaps more importantly, these servers can also be centralized into one or two data centers, driving down labor costs while increasing server utilization. Sun Java System Communications Services software can be deployed in a centralized manner because the bandwidth-efficient communications protocols (including IMAP and SMTP) that are used between the Sun server software and the desktop client enable the server to physically reside far from the client.
In contrast, Microsoft Exchange cannot be centralized nearly as well as Sun Java System Communications Services software. This is largely related to the MAPI-based architecture used to connect Exchange and Outlook and its reliance on the Remote Procedure Call (RPC) networking protocol for client-server connections. An RPC-based solution, requiring multiple servers due to the heavy nature of the protocol, doesn't perform as well as IMAP and SMTP, which are used by Sun Java System Communications Services. With Microsoft Exchange, you end up with a highly distributed communications platform consisting of scattered islands of messaging data. This imposes heavy synchronization requirements, especially for public mail folders, calendar folders, and so forth.
Microsoft even recommends deploying additional Microsoft Exchange “cache” machines, especially for mail traffic, which consumes a great deal of network bandwidth. On the contrary, an IMAP-based product like Sun Java System Messaging Server benefits from using an IMAP design, which was, since its beginning, optimized for bandwidth efficiency. This explains why IMAP is so important for the telecommunication and service provider markets. These markets, whose third generation networks enable client devices direct IP access to mobile operator's infrastructures, depend upon IMAP. These markets also are counting on extensions to the protocol, such as those provided by the Lemonade IETF working group, to provide new services in the future.