Former Richland County Sheriff and mail carrier Allen Prochnow entered a plea of guilty of delaying and destroying mail.  The Wahpeton man failed to deliver nearly four tons of mail between 1998 and April of this year.  Federal agents found the mail during a search of Prochnow’s home last spring.  Sentencing will be in March with recommendations for probation being made as part of a plea deal.  The US Postal Service is planning to deliver about 3,000 pieces of first class mail found in Prochnow’s home.