It's a scam.
There's a good chance someone is expecting a delivery from AnPost due to the sheer numbers of parcels they deliver, so the scammers might send out 5,000 textx and 500 of these are expecting a parcel.
They then lure you in by giving a very small amount that you may think nothing of.
In a way the text is plausible as companies add on a cost for almost everything, however An Post do not charge for such a service and almost all of their parcel customers have address label automation, so unless you have entered the address wrong, the label is as you put on a website.
Delete and block the number