I use Pos Malaysia Flexipack to send small pcb back to Shenzen all the time, make sure add AR register so you can track real time,

never heard? it's there all the while

use Pos Malaysia Flexipack International Prepaid Envelope and add AR Register form to track the package online..That is the most cheapest way to post items Internationaly, I use it all the time and touch wood never lost any package (due to traceable AR Registered)