Working with MSMQ can be hard. Windows does not provide a tool to generate or edit messages on the queue. There are plenty of tools that can do that for you. Especially I like Mqueue Viewer
Authors describe Mqueue as Fast and free MSMQ management tool, to manage your messages and queues and I totally agree with that statement.
Some screens below can give you a better understanding.
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I think it is worth keeping such a tool in a dev-toolbox. You can download it from http://www.mqueue.net/