That's the trouble with Coinbase isn't it? Anyway, by default, if that email exists, I suppose whoever controls it will now get your email inviting them to open a Coinbase account and claim your money. If that email doesn't exist (doubt it doesn't but probably a catch all address) or no one actually signs up to register, then you will get a refund in 30 days.
Try sending an email to
a@aol.com, who knows, someone replies? You could try contacting support as PC says, but they're not likely to do anything about it until after 30 days.
P.S. Isn't it time to use a proper Bitcoin wallet, like say, Electrum? Less likely to "accidentally send to random address".