Pincushonass wazaaaaaaaap...
He means local mail, US. Am I right? Overseas ones or local, I think are OK to receive at mailboxes, etc. If it would be seized then it would happen in customs, not at your local MBE. So, you are alright, man...
never had any problems personally, but have heard of the good ol' MBE set up by the bad guys. doesn't really matter where you ship your gear to. if they want to get you they will get you, if not you'll be fine.
I import items all the time to my MBE box.....use a fake business name when you set up your box and have all the items sent to the business name. As long as your only ordering for personal use, you should be fine...