Delta Air Lines allows SkyMiles to earn award miles, Medallion Qualifying Miles (MQMs), Segments (MQSs), and Dollars (MQDs) on flights within Alaska.
The only small print is that only flights operated by airlines without their own frequent flyer program are eligible, and they must be issued on Delta’s ticket stock 006.
You can access Delta’s page for partner airlines here.
Here’s the announcement from Delta:
More Ways to Earn Miles with Other Airlines
Beginning with travel on April 15, 2021, SkyMiles Members can earn miles and earn towards Medallion Status on flights within the state of Alaska that are ticketed by Delta (the ticket number begins with ‘006’) and operated by a carrier without its own frequent flyer program.
Members will earn miles and earn towards Status just like they normally do on Delta-ticketed flights.
Be sure to add your SkyMiles Number to your reservation prior to travel so that your miles are credited automatically after you travel.
Offer Terms & Conditions
Mileage accrual for SkyMiles members traveling on/after 04/15/2021 on any intra-state Alaska flight operated only by a carrier that does not offer its own Frequent Flyer Program. Travel must be booked through delta.com or any Delta authorized sales channel. The qualifying electronic ticket for intra-Alaska eligible flight must be issued on Delta (006) ticket stock only. Customer should include their SkyMiles account number onto Delta’s reservation record locator during booking. If a SkyMiles account number was not added to the reservation prior to travel, customer may, within 9 months of completion of the flight, request a retroactive credit. If a SkyMiles Number is added to the reservation prior to travel, the miles will be credited automatically with no action needed from the SkyMiles Member.
Delta here probably refers to small carriers that connect remotes communities within Alaska that Delta serves through local small airlines. You can now earn Skymiles, MQMs, MQSs, and MQDs on those flights too.