Flying to Copenhagen from ATL, change planes from Delta to KLM in AMS. Do I have to go through immigration/customs in AMS or simply go the the next gate and do the immigration in Copenhagen. Will I have to pick up my bags in AMS and recheck them?
Are you traveling to CPH with a connection at AMS? I.e. ATL to AMS to CPH. If yes, and you stay planeside at AMS, passport control/immigration at AMS then customs at CPH. Delta/KLM should check your bags through to CPH. Most people do the "green" customs nothing to declare exit after picking up their checked baggage.
We just did this same flight two weeks ago and the previous poster is correct. Luggage checked through, passport control at AMS and customs at Copenhagen, however since we were just arriving we had nothing to declare so walked through the green doors.
If your connection in AMS is tight be sure to listen for the man lokking for people with a short connection time, he'll move you to a shorter line. If you don't hear him announcing it then look for the line on the far right. They had someone there looking at boarding passes before allowing you to pass through. Have a great time, I loved Copenhagen.