All of them are the same in meaning but "띄우다" is often found in song lyrics.:) The others are commonly used in everyday Korean, and they have nothing to do with objects they take. \^o^/

The verb 보내다 is usually used in most caes in the meaning of sending something to someone. 편지를 보내다 소포를 보내다 짐을 보내다. The verb 부치다 is also used in a sense of asking a person to deliver a letter or parcel. 편지나 소포를 부치다. 짐이나 선물을 부치다. And basically, the verb 띄우다 is derived from the ancient communication tool, signal fire/smoke, that is, lighting a signal fire by night or rasing a signal smoke by day on a beacon mound. 봉화나 파발을 띄우다. 편지나 전보를 띄우다. 연락이나 소식을 띄우다.