Working with envelopes in BizTalk Server is always a little tricky. This sample shows how to use an envelope to de-batch a larger Xml message.

Some Key Take Home Points:
– De-Batching / Envelope Processing for XML Document must take place on the Receive Port. I have not been able to get it to work on the Send Port, but I am still trying.
– Properties can be promoted from the Header and demoted to the single messages
– No custom pipelines are required for Receive Port Processing as long as the Root Node Name and Namespace are unique throughout your entire deployed solutions.

Get more information from the original blog post on this topic: