The eBay Feedback system does not allow you to leave Feedback for someone who is not a registered user.

This doesn't necessarily mean that you will never be able to leave Feedback for your transaction with them. The item will remain in My eBay for at least 90 days, and if the member is reinstated within that time, you can leave Feedback for the member then.

However, if the member's registration does not become active again, or if it doesn’t become active until after 90 days, you will not be able to leave feedback for this member.

If a bidder has become "no longer a registered user" since winning your auction, don't send them the item until payment has cleared. If they don't send payment, you can file an Unpaid Item Dispute to claim your Final Value Fee. Since the buyer is unregistered, you'll be able to close the dispute and request a credit immediately. eBay will remove negative and neutral Feedback left by members who are suspended.

Note: "Not a registered user" can refer to members who have cancelled their membership, or whose membership has been suspended by eBay. For example, a member whose correct contact information is no longer on file with us may have their registration suspended until the new contact information is entered. In either case, the member appears as "not a registered user" and is not allowed to buy or sell on eBay, unless they become reinstated.