Particle sniffers are used in Australia but as sixes rights points out they can easily be defeated with the right packaging methods. Regarding the most recent joint AFP and customs operation in Australia they are x-raying entire pallets of letter mail looking for organic matter which would explain the massive disruption to the mail service. What an utter waste of time and tax payers money, it is disgraceful they can cause so much disruption for the tiny fraction of drugs that comes via the mail.