Regardless of what the RCMP says, that does not make it a law... The laws in regards to firearms are contained in the firearms act, which states:
Shipping by Post
16 An individual may ship a firearm by posting it only if
(a) the firearm is a non-restricted firearm, restricted firearm or prohibited handgun;
(b) the destination is within Canada; and
(c) the firearm is posted using the most secure means of transmission by post that is offered by the Canada Post Corporation that includes the requirement to obtain a signature on delivery.
So, shipping by means other than Canada Post is illegal......