They seize it, you got a letter from the customs. You have 3 option:
-Let them burn it
-Contest the seize (no chance)
-Send it back to the sender. You have 1 month if I remember to do that
That take like 2 week to finally send it back but you receive the letter 2 weeks after the seize so...
For blacklist, not all the time. I'm not blacklisted. I import alot of other thing (ebay, airsoft accesories) and no package were open.