When mailing is required by Section 21 et seq. of this title, the mailing shall be made by the court clerk or a deputy court clerk or by the attorney for the party and proof of the mailing shall be by affidavit of the court clerk or deputy court clerk or attorney filed in the case. Any mailing made pursuant to this section after June 22, 1988, which is in compliance with the provisions of this section at the time this act becomes effective, shall be deemed to be in compliance with this section.
Okla. Stat. tit. 58, § 34