Neither rain, nor sleet, nor snow, nor terrorist attacks can prevent the U-S Postal Service from keeping its appointed rounds. Rich Watkins, spokesman for the U-S-P-S in Iowa, says mail service has been slowed but by no means has it been stopped.Watkins says Iowans should -not- be concerned about their mail being delivered — ground transportation will be used instead of air. He says it may not be quite as fast, but the task of delivering envelopes and parcels is continuing. He says they hope to move as much mail as they can.All post offices in Iowa are open regular hours.