A FAQ attach to the original memo:

"Will our Platinum and Gold Medallion members, (Silver, Gold and Platinum) continue to be exempt from the 51-70lbs excess baggage charges? Will that apply to golf bags and ski bags?
Yes, our PMs, GMs, FOs and those passengers traveling in First/Business class cabin will still be allowed to check up to 70lbs at no additional charge and that will apply for golf equipment and ski/snowboard bags on Delta and DCI operated flights only."