I received an e-mail from the Apple Store for a purchase I did not make

Check your iTunes account:

If you see 'itunes.com/bill' or an unfamiliar charge on your statement - Apple Support

If it's not there then it may be phishing:

Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

 In a message Apple will always address you by your real name, never by your email address or Dear Customer. Also the sent-from address should be @apple.com or @itunes.com Additionally Apple does not send attachments.