My post office encourages me to mark items as a gift, and sometimes if I haven't added the little green sticker myself, they'll do it, and mark it as a gift. In general, I don't really care. Most of my stuff is worth less than $20, so buyers aren't going to get charged any kind of duty or anything anyway. That's all the declaration does, by the way. It just lets the receiving postal company know how much to charge the receiver for taxes, if applicable. I don't usually mark the "gift" box, but like I said, sometimes my post office does. No big deal at all.