I have sent out more than hundreds of pos express from my epikcase bulk.
Yeah, I do face some problem but the ratio is very very small.

Normally the area under zone A is "dijamin sampai esok" but sometimes it will delay a few more days. Or sometimes, already been posted but the recipient didn't check the mailbox carefully.

I will rate pos express so far so good. They recently increase the price but it is still the cheapest way to send small stuff out.