Couldn't be simpler!

[hiretsukan]

void Insert(ref object ExtractAddress, ref object Address, ref object AutoText, ref object OmitReturnAddress, ref object ReturnAddress, ref object ReturnAutoText, ref object PrintBarCode, ref object PrintFIMA, ref object Size, ref object Height, ref object Width, ref object FeedSource, ref object AddressFromLeft, ref object AddressFromTop, ref object ReturnAddressFromLeft, ref object ReturnAddressFromTop, ref object DefaultFaceUp, ref object DefaultOrientation, ref object PrintEPostage, ref object Vertical, ref object RecipientNamefromLeft, ref object RecipientNamefromTop, ref object RecipientPostalfromLeft, ref object RecipientPostalfromTop, ref object SenderNamefromLeft, ref object SenderNamefromTop, ref object SenderPostalfromLeft, ref object SenderPostalfromTop)
Member of Microsoft.Office.Interop.Word.Envelope

Word Automation function declarations are like punchlines. Documentation? What documentation???