"At the time of this writing, the average volume of messages submitted from the Internet to Microsoft IT e-mail gateways ranges between 10 million and 12 million a day. The multilayered approach to e-mail filtering means that multiple mechanisms analyze incoming e-mail, and each of these mechanisms subsequently reduces the amount of spam permitted to pass. The following filtering stages illustrate the effectiveness of e-mail filtering layers in Microsoft IT as of this writing. The percentages are based on average daily volumes. Connection filtering blocks approximately 80 percent of all incoming SMTP messages. These connections come from known spam sources listed in third-party, real-time block lists. Sender and recipient filtering deletes 70 percent of the messages received after connection filtering. After connection filtering, sender filtering and recipient filtering remove almost 95 percent of messages as spam. Intelligent Message Filter rejects 6 percent of the remaining incoming messages as spam."
"Managing this messaging infrastructure is a formidable task. For approximately 92,000 employees, the infrastructure supports 116,000 mailboxes, each with at-least a 200-megabyte (MB) storage limit. Global e-mail flow totals, on average, more than 12 million messages per day; 3 million of those are internal e-mail messages. Each day, approximately 95 percent of incoming e-mail from the Internet is filtered out as spam, virus-infected e-mail, or e-mail addressed to invalid addresses."
Managing Exchange Messaging Services by Using Metrics:
"The Exchange messaging infrastructure at Microsoft is a large messaging environment that consists of:
- 116 servers running Exchange Server 2003 (including passive clustered nodes), of which 63 of the 69 mailbox servers are in clustered configurations running Windows Server 2003. - Four Exchange sites in regional data centers worldwide. - Messaging services for approximately 102,000 users. - More than 118,000 total mailboxes (including system mailboxes). - 200-megabyte (MB) storage limit for each mailbox. - More than 10 million messages globally per day. (Approximately 3 million are internal e-mail messages.) - 20,096 Smartphone devices that access Exchange. - 5,145 mobile devices running Windows Mobile version 5.0 that access Exchange. - 2,279 devices not running Windows Mobile but using an Outlook Mobile Access connection. - 60,482 users connecting to Exchange by Outlook Web Access 2003. - Approximately 60,000 users connecting to Exchange by remote procedure call (RPC) over Hypertext Transfer Protocol (HTTP) and Outlook 2003."
"In the past, Microsoft IT monitored and managed the Exchange messaging infrastructure at Microsoft as a stand-alone technology, rather than as a service that relies on many other technologies and operational groups. In other words, Microsoft IT monitored and managed individual servers or services running on servers. For example, Microsoft IT measured Exchange availability from solely an operating system basis of how long the Exchange back-end servers were running. This practice provided an incomplete view of actual service availability because users may not be able to access the Exchange servers because of other infrastructure outages or performance-related problems.
Today, Microsoft IT monitors and manages the Exchange messaging infrastructure as an end-to-end business service, based on actual measurements from client computers, a more comprehensive server application availability, message latency measurements, and customer satisfaction surveys. In addition to providing accurate information about performance, this factual, realistic perspective on Exchange messaging services provides IT managers and decision makers with the necessary information to manage the Exchange messaging infrastructure. The shift in management methodologies also enabled Microsoft IT to improve user satisfaction and increase employee productivity."