United States Government--post Office Saint Jacob, IL 62281 Phone : (618) 644-5603 Business Category Government Offices-Federal Post Offices Government Offices & Public Schools Post Office - Saint Jacob 309 N Douglas St Saint Jacob, IL 62281 Phone : (618) 644-5603 Business Category Government Offices-Federal Government Offices-State Post Offices Government Offices State & Local Government Offices & Public Schools Toll-Free           (800) ASK-USPS