In MSMQ, all computers that run MSMQ belong to one enterprise and access information from the same distributed database, called the MSMQ information store(MQIS). To simplify administration and for compatibility with future versions of Windows NT Server, you should not install multiple enterprises within your organization. Issues relating to security and isolating the use of MSMQ between groups within your organization can be addressed using MSMQ security features.
However, if you choose to have more than one enterprise within a company, or want to exchange MSMQ messages with another company (for example, over the Internet) you can still do so. For information on sending messages between enterprises, see the MSMQ SDK.