Ill. Admin. Code tit. 11, § 1900.1160
e) All wagers shall be redeemed in United States currency. The currency amount may be provided to the patron in any form that has been documented in the internal control system, subject to the following minimum requirements:
f) A master sports wagering licensee may provide for redemption of winning tickets or refund of void or canceled wagers by U.S. Mail. In that case, the licensee must document methods in its internal control system to provide for compliance with all other rules, including but not limited to: