MQDs are the total of the SkyMiles member’s spend on Delta-marketed flights (flight numbers that include the “DL” airline code), inclusive of the base fare and applicable surcharges, but exclusive of government- imposed taxes and fees.
Flight spend for travel on other airlines ticketed through a Delta channel (featuring a ticket number beginning with “006”) will also be included in MQDs.
http://www.delta.com/content/www/en_...lars-faqs.html
This is a serious blow to Skyteam. For instance, if you buy an AF or KL ticket on their stock it will NOT earn MQDs.