Unless otherwise provided by law or contract, the recipient of a digital signature assumes the risk that a digital signature is forged, if reliance on the digital signature is not reasonable under the circumstances. If the recipient determines not to rely on a digital signature under this section, the recipient must promptly notify the signer of any determination not to rely on a digital signature and the grounds for that determination. Nothing in this chapter shall be construed to obligate a person to accept a digital signature or to respond to an electronic message containing a digital signature.