For open-end credit, Regulation Z requires that you include any loan payments on periodic statements. 12 CFR 1026.7(a)(3). Otherwise, we are not aware of any federal or Illinois laws that would require you to send a notice when a loan matures or when a customer makes a payment on a loan. We do recommend that you check your loan agreements to ensure that they do not include any such notice requirements.
As to postage costs, note that both the Illinois Financial Institutions Electronic Documents and Digital Signature Act and the federal Electronic Signatures in Global and National Commerce Act (ESIGN) allow financial institutions to send notices electronically, if you meet all of their consumer consent and notice requirements. 205 ILCS 705/1015 USC 7001.