While not exclusively Baptist, Chapel Library (affiliated with Mount Calvary Baptist Church) distributes printed Puritan and Baptist history courses. They will pay the postage both ways if you cannot afford it.
This ministry provides "Great Doctrines Of the Bible," a series of 36 lessons. You can earn certificates or a diploma by registering via mail. free baptist bible correspondence courses by mail link
For those who prefer a physical, mail-based learning experience—or lack reliable internet access—several Baptist ministries and independent Baptist churches still offer free Bible correspondence courses by postal mail. These courses typically include printed lessons, fill-in-the-blank or multiple-choice questions, and personalized feedback from a pastor or mentor. Upon completion, many provide certificates or even small study Bibles. While not exclusively Baptist