The question to ask here is the same one you ask when you get an email saying you've won the lottery. But instead of "Did I ever buy a ticket for the lottery?" in this case it would be "Did I ever buy a ticket from American Airlines?" If the answer in either case is "no", then it's patently a scam and following a link or opening an attachment is potentially dangerous. Having a Mac, you may have got away with it...
Friend yesterday had several emails purporting to come from DHL, with a click here for parcel tracking. It all looked genuine apart from the 'Hello Dear' at the start! Oh, and he hadn't ordered anything.
Know you have marked this as resolved but just wanted to tell you that I had the same e-mail from American Airlines in November, different price etc., and was lucky that I cannot open anything in the format they sent, because curiosity did get the better of me!!
Checked credit card company, bank etc., and up to today no money has been taken.
Incidentally, I googled the airline and it appears to be ligit, but experiencing financial problems etc.
It's a scam. Variants of this have been around for a few years now. Do not open but delete immediately. It is not from American Airlines. If you look closely at the message properties you find out but unless you have a robust anti-virus I do not recommend doing this.