Here's how it goes.
You NEVER use UPS or Fed Ex, they can and do open packages on a whim.
You always do use the United States Postal service. It requires a court order from a judge to actually open a package when using USPS.
Also you may have noticed a small sign at the post office that reads something like this "All mail over 12 ounces in weight, can't be sent by dumping it into a mail box with stamps on it. It has to be metered by a live postal agent.
That's your cut off point, 12 ounces or under including box and packaging weight. So yeah, more then a couple ounces a 1/4 max and your package takes on new meaning at the post office.
Having said that, ordering and shipping small amounts of weed, is much safer and easier then having seeds shipped from a foreign country.
The penalty if your caught is actually potentially much less. Look at Marc Emery, they wanted to give him a life sentnence for being a bean dealer.
My friend BC Bud, had 300 packages of dope go missing, I told him to stop immediatly but he didn't, he got caught with his pants down. And did about a 1 and 1/2 in a canadian jail. He's right back in the game now though.