My experience is that Delta is pretty honest in posting miles. Even if they missed it, you emailed them, and they will post it promptly. They will not pretend they've never ran the promo.

The dishonest award for me goes to AA & CO.
AA : always (and I mean 100% of the time) will not post any shopping points until I emailed them at least twice. They never do it automatically, and they'll never post even after they promised to.

CO : Even worse. I'm still fighting for a couple hundred miles from last Feb. I bought from same retailer twice in a month, but CO will NOT post the 2nd one. I guess it's not in their blood to check the order #. And they don't care.

And forget about the award. The award calendar shows availability, but when you click on it, it'll show completely different sets of awards.