Voldemort was about to disapparate to Hogsmeade to meet Natasha when the owl arrived. When He saw who she addressed it to, He torched the owl with fiendy fire. He wasn't sure what incensed Him more: Her gall to use His birth name or that the owl would deliver such letters to Him.
He spent several minutes contemplating how to respond. He didn't sincerely think she would turn over all the information the Ministry had n Him, but He had retained a hope that she would give Him something worthwhile. He also knew that she was willing to go to great lengths to protect her family. Was it worth sending this back?
Remember this choice in a week. I'll see you at your grandson's funeral. His won't be the last funeral of a loved one you will have to attend.