Shared Exchange describes where a service company hosts multiple companies on a single Exchange environment. This is in contrast to hosted Exchange, which is where a service company hosts at their site the dedicated Microsoft Exchange infrastructure for another company. Exchange 2000, which was introduced in 2000, was the first version that could be feasibly deployed in a hosted shared Exchange model. Configuring shared Exchange was and is a complex process. The use of a provisioning solution such as abrideanProvisorSP provides the accuracy and efficiency required for a commercially successful shared Exchange offering.
Companies offering shared Exchange include MailStreet.com and USA.NET. Many of these companies offer additional services such as SharePoint and Blackberry/RIM support. Users of shared Exchange range from single users and "Mom and Pop" businesses to large corporations such as United Airlines.