There are a rich array of parcel carriers available, and many will be cheaper than the Post Office. This is important, of course, if you have volumes to send, but never forget to consider service levels too. They vary a lot from carrier to carrier. We moved, some time ago, to a combination of FEDEX and DPD, since which we have reduced the number of delivery related snags noticeably. Both are reasonable without being the cheapest, although their prices may vary with projected volumes.
Some carriers really do just pop the bag next door and disown the problem. And you would be surprised how many next doors don't have the parcel. Apparently.