If you were coming back from
If you were coming back from somewhere and you’d taken a bike box out with you – it would be pretty hard to check, although I suppose if they really got suspicious they could cross check to see what it weighed (or more likely what it cost you because of what it weighed) to bring it out. That’s pretty unlikely, as to Bananadrama’s point about it being scanned at the security gate, well you would’nt be taking it on has hand luggage would you, it would be going as hold luggage which might very well get scanned but unless it raised suspicions is not going to be linked to a particular passenger – you only have to see how hand luggage is dealt with to notice that.
However, Gandberg’s original question was about getting something shipped over without him having to go out and get it.