Jubal told him that it was otherwise all right to keep anything that came to Mike by parcel post provided that none of it was (a) ever paid for, (b) ever acknowleged, (c) nor ever returned no matter how marked.  Some of the items were legitimatly gifts; more of it was unordered merchandise.  Either way, Jubal assumed conclusively that unsolicited chattels from strangers always represented efforts to make use of the Man from Mars and therefore merited no thanks.