I tried searching but couldn't come up with anything. I'm trying to check-in online via the website and the email check-in link. (I'm returning to ATL from a few days in CUN. I had no problems on the way down.) I receive a message about not being able to do it. The email response from Delta appears pretty general: We apologize for any inconvenience you experienced in regards to online check in. There are some restrictions that may not let you check-in online. Common examples of these may include: - Schedule changes (voluntary or involuntary) - Upgraded itineraries (which have not been reissued) - Certain international itineraries - Credit card presentation required - Special Service Requests in the reservation Does anyone have any experience with this issue? Thanks!