Okla. Stat. tit. 58 § 331.2
After notice is given as required by Section 331 of this title, an affidavit of mailing and, if applicable, of personal delivery, and an affidavit of publication must be filed with the district court clerk. The affidavit of mailing, and, if applicable, of personal delivery, shall be made by the personal representative and shall state words to the effect that the personal representative personally, or by and through the personal representative's attorney, mailed notice by first-class mail to all creditors of the decedent known to the personal representative on the date said notice was filed with the district court clerk for the county in which the probate is pending. Said affidavit shall also state the identities and last-known addresses of such creditors and the date said notice was mailed or delivered. If the decedent had no known creditors or had one or more creditors whose addresses were not known to the personal representative as of the date said notice was filed, there shall be filed an affidavit of the personal representative to the effect that nomailing is required and the reasons therefor.
Okla. Stat. tit. 58, § 331.2