R.I. Gen. Laws § 45-6.1-4: Time and manner of payment.

(a) The ordinances referred to in § 45-6.1-1 establish times during which the privilege of paying the fine by mail may be exercised, but the time shall be not less than five (5) days from the date of the offense to the date of depositing the payment of the fine in a depository maintained by the United States post office department for the collection of mails.

(b) Any non-moving traffic violation fines are deemed to have been paid upon the date of mailing and the postage cancellation is prima facie evidence of the time of deposit.