I'm not sure about SAL specifically, but personally i think it all depends on who's delivering sometimes!

I've had registered parcels/regular mail from australia/US either
a) delivered to the door with a knock
b) thrown at the door and left (this happened today infact, among other times - luckily just some dvds that were well packed)
c) left outside on the mailbox (even when they'd easily fit in)
d) left with a note to pick them up (even when they'd easily fit in and my office was definitely occupied)
e) actually in the mailbox

That's probably not encouraging, but i guess they haven't completely lost anything i've ordered!