Request for clueful person at Apple's mail operation

Folks, A number of colleagues have been having delayed or rejected mail deliveries (with "451 4.5.3 Too many rejections; try again later." messages) since Saturday morning. Apple's front-line iCloud support people have been helpful, but not terribly clued in. Could someone contact me off-list to talk about this? Many thanks. Rich Brown Blueberry Hill Software richb.hanover@gmail.com +1 603-262-3957 (land line)