Generally no, they will probs issue warning for small amounts, its not worth the time/resources to investigate personal use, all for what a pissy slap on the wrist?
They generally target large imports, where someone is set to make alot of money, and likely to get put in jail . If there is a big quiet period then they might bother with small amounts.
Generally with the amount of mail that goes thru those places, dogs are used to sniff mail n parcels. Also you cant really import much with a envelope, as has to be under certain weight size, so focus is on parcels.
But that is a risk you have to take, no one is forcing u to
