If you receive an iTunes gift via email, but don’t want to open iTunes, do the following to redeem the gift in a different program (e.g. App Store or iBooks):

1. Open the email with the iTunes gift
2. Right Click on the "Redeem Now" button and copy the link. The menu option is usually called something like "Copy Link" or "Copy Link Address…"
3. In a text editor paste the link. The link should look something like https://buy.itunes.apple.com/WebObjects/MZFinance.woa/wa/com.apple.jingle.app.finance.DirectAction/freeProductCodeWizard?code=XABCD1234ABCD12X&mt=1M
4. The gift card code (same as scratching off a physical gift card) is the text between "code=" and "&mt". In this example it is XABCD1234ABCD12X (not a real gift card code)
5. Paste or type this code into the Redeem page of any of Apples app stores