Within 5 days after the adoption of a resolution authorized in section 303, the county clerk shall forward a copy of the resolution, together with a letter indicating where an electronic or paper copy of the tentative 9-1-1 service plan can be obtained, by certified mail, return receipt requested, to the clerk or other appropriate official of each public agency located within the 9-1-1 district of the tentative 9-1-1 service plan.