Assembly: Microsoft.Office.Interop.Word (in microsoft.office.interop.word.dll)
There is no Envelopes collection; each Document object contains only one Envelope object.
Use the Envelope property to return the Envelope object.
The Envelope object is available regardless of whether an envelope has been added to the specified document. However, an error occurs if you use the Envelope property. UpdateDocument method or one of the following properties when an envelope hasn't been added to the document: Address, AddressFromLeft, AddressFromTop, FeedSource, ReturnAddress, ReturnAddressFromLeft, and ReturnAddressFromTop.