Originally Posted by
danielvdm
Is this in J or Y? Speaking generally, you'll probably get more MQDs if you book through AM and credit to DL. Depending on the fare class, you'll earn MQDs as a percentage of your miles flown. (Check the delta partner earning charts). Cheap AM J fares are a pretty popular hack to getting cheap MQDs.
It's only the marketing carrier that matters for earnings, not the ticketing carrier.