Checked bag on Delta

[eticketplease]

I think it knows because you enter the Delta Amex as your method of payment in The delta app.

As others have pointed out, delta knows that you have the American Express card to allow it free bags via your SkyMiles number. This is the same way that you’ll see discounted redemptions when going to book if you have a gold or higher card you’ll get 15% off the miles. You do not have to use your card to get a free bag. Just have to hold the card and pay the annual fee.

 

[sam_gordon]

I think it knows because you enter the Delta Amex as your method of payment in The delta app.

As mentioned, you don't need to use the Delta AmEx to pay for flights, seats, or checked bags. I believe one enters their SM# on the AmEx site, but not positive. Either way, the AmEx should be linked to your SM account.