My guess as to why it takes longer to post those "certificate" type of miles as opposed to "flight" miles is that it is a manual process whereas the flight miles are computerized. In other words, someone has to "data enter" your certificate when it is received at the center. That defintely would add time. The flight miles probably just automatically post from whatever system they use for res (not sure if Delta is on SABRE?) to the SkiMiles system. Just my opinion Keep all your receipts and you'll be fine. When I sent in my AA Healthy Choice certificates, I sent them certified with return receipt because I too worry

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