To purchase a gift certificate for someone, you need to enter an email address for the recipient. The order will not go through unless a recipient email address is entered. The Gift Certificate feature is designed for online use only. If the recipient does not have an email account, then you may enter your own email address instead. Print out the email with the gift certificate code(s) and give it to the recipient.
If the amount that is spent is less than the Gift Certificate amount, the customer will have a credit for the Gift Certificate code and will be able to use that code again. Unused credit will not be refunded.
Need more information on Gift Certificates, visit How do I use a Yahoo! Store gift certificate?