Forgot to add, while I was still debating the conflicting instructions for 2019 filing to mail or not mail the AR8453-OL, I almost immediately got my AR refund deposited in the bank and have never received any follow-up complaints about not mailing the form. I note that the AR8453-OL on my 2019 TurboTax return which has the "DO NOT MAIL" instruction has revision date 5/31/19 while the form with mailing instructions at the URL pointed to by previous response appears to be an obsolete version with a revision date of 10/1/07, which is prior to the law change for tax year 2011 and following.
