i recieved a email for a app purchase that i did not purchase

Are you sure the message is legitimate? Does it contain a link for you to sign in somewhere? It may be a scam.

Apple will always address you by your name or the name they have on file for you and the e-mail will be from @apple.com.

Avoid phishing emails, fake ‘virus‘ alerts, phony support calls, and other scams

Identifying legitimate emails from the iTunes Store

Send the e-mail to Apple as an attachment to a new e-mail before deleting it.

reportphishing@apple.com

It is very possible that the email is not genuine Apple and is a phishing attempt. See this for help in identifying fraudlent messages. Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

Apple will always address you by name, not Dear Customer, or Dear <Apple ID>

If you hover over the email address with a mouse, the email address should be from apple.com.