A stone structure mailbox is rather permanent and you need to decide on a design before you begin. To check out the many styles and materials, you can use a computer program that will allow you to experiment with different styles, etc.
Remove the mailbox and post. Clear out a space in the mulch so you can level the ground.
Dig the footer six inches deep and level up the base.
A footer should be at least six inches thick and six inches wider than the mailbox. If you live in an area with cold winters, dig the footer deep enough so that the base rests below the frost line.
Make sure to mix enough concrete to fill up the footer.
Pour half the concrete into the footer.
Lay out a 12" x 16" block in the center with the long side facing the street. Mark it on the footer to use as a guide for setting the first layer of mortar.
Note: It is critical to get the first block level because you do not want a leaning mailbox.
Insert wall ties that will help support the stones later on. Continue laying blocks making sure they are all level.
Wall ties are installed during the construction process in the masonry joints. The ties will adhere the stones to the cinder block wall and ensure that it will not pull away over time.
Set a 12 x 16 x 14 cap block to serve as the base for the newspaper holder and mailbox.
An easy way to keep the block level when you are laying it is to place a three-foot carpenter's level across the top of each one as you set it in the mortar. That way you can see at a glance when the block is properly set.
Notch out the cinder blocks for the boxes by cutting the ends toward the paper holder. Set them on the cap block placing the cut ends toward the paper holder. Add mortar around the holder and keep it in place. Set another 4-inch cap block in place -- this block will be the base for the mailbox.
Cut the cinder block the same as before, but this time set them on their ends to clear the height of the mailbox. When the mortar sets up, you will have a sturdy base to set the stones around.
After constructing a cinder block wall, you should let the mortar cure at least overnight prior to adding any more weight such as face brick, or stone to the structure.