Colombia's official postal service is the terribly named 4-72, which has turned the debilitating pension liabilities and inefficiency of Colombia's former government postal service, Adpostal (shut down in 2006), into a profitable and efficient business.
If you want to receive a package in Colombia, you have a choice. The sender can ship via a courier like DHL, which guarantees fast, dependable delivery, but also guarantees Colombian customs will open the box and charge often exorbitant duty. If you're not hurried, have the package sent via regular airmail (four to eight weeks).
Identification is required to ship packages or letters from Colombia, so head to the post office with your passport.