With a gift voucher you can choose your preferred email address and instead of paying, you just enter your 16 digit voucher code when prompted.
If you got your gift voucher sent to you by email, please click on the link in the email to go to the website where you can get your email address.
If you received a printed Gift Voucher go to the website listed on your gift voucher and you can then choose your preferred email address.
You'll see on the order page there are 2 payment methods:
Choose Voucher and then follow the steps.