Idaho Code § 45-1508
A sale made by a trustee under this act shall foreclose and terminate all interest in the property covered by the trust deed of all persons to whom notice is given under section 45-1506, Idaho Code, and of any other person claiming by, through or under such persons and such persons shall have no right to redeem the property from the purchaser at the trustee's sale. The failure to give notice to any of such persons by mailing, personal service, posting or publication in accordance with section 45-1506, Idaho Code, shall not affect the validity of the sale as to persons so notified nor as to any such persons having actual knowledge of the sale. Furthermore, any failure to comply with the provisions of section 45-1506, Idaho Code, shall not affect the validity of a sale in favor of a purchaser in good faith for value at or after such sale, or any successor in interest thereof.
Idaho Code § 45-1508