I have a friend who was flying DL exclusively for 3-4 years and managed to rack up a rather hefty mileage total in his account. He stopped traveling as much and when he went on to his account (Jan 2009 -ish) was surprised to find his miles had all expired. Miles can be re-activated on DL.com for a fee if they've expired less than 2 years ago. https://www.delta.com/skymiles/manage_account/reactivate_miles/index.jsp?src=d We called today and got an awesome CSR who looked into it and was able to over-ride the 2 year limit. At first the CSR didn't think it was possible, but after looking into it she was able to do it! IMO getting over 200k miles back for a 20 minute phone call and $250 was well worth it. Just wanted to let everyone know that it is possible to re-activate an account that has expired more than 2 years ago.