I tried that but when I went to the post office they told me "no", because if it is bulky then it is considered a parcel. So I print my own labels at home to make it even cheaper than what the post office charges.
you can put it in a bubble envelope. my mother works for the post office. it will be fine. it is no cheaper to print labels at home vs in yhe pist office. if u just out it in a bjbble envelope so its padded and do it by weiht it will be much cheaper.