Messaging throughput is limited by the hardware being used. Processing power, available memory, and network capacity have the greatest affect on messaging throughput. The number of messages each MSMQ independent client and server can store at one time is limited first by the available disk space on the local computer, and second, by the code and data space of the operating system on which MSMQ is running.
When running Windows 95, MSMQ independent clients can store close to 1 gigabyte (GB) of messages. Specifically, MSMQ independent clients can store 1 GB of messages minus the memory consumed by the overhead of storing the message and the memory of other applications using the shared system memory.
When running version 4.0 of Windows NT Workstation or Windows NT Server, MSMQ independent clients and servers can store just under 2 GB of messages (specifically, 2 GB minus 20 MB).
On all platforms, each MSMQ message can have no more than 4 MB of data.
For MSMQ servers supporting multiple MSMQ dependent clients, this limit applies to the server, not each individual client. For example, an MSMQ server supporting three dependent clients can hold no more than a cumulative total of 1.98 GB of messages for the three dependent clients.