Document.MailMerge (Word)

Returns a MailMerge object that represents the mail merge functionality for the specified document.

The MailMerge object is available regardless of whether the specified document is a mail merge main document. Use the State property to determine the current state of the mail merge operation.

Set myMerge = ActiveDocument.MailMerge 
If myMerge.State = wdMainAndDataSource Then myMerge.Execute