Choosing a Mounting Post

Which Mounting Post is Right for my Mail Boss?

When contemplating this question, there are two USPS installation requirements for curbside delivery mailboxes that must be considered:

How do you determine which mailbox post is right?

  1. The base of the incoming mail slot (where the mail person actually inserts your mail into your mail box) must be 41” to 45” vertically above the road surface on which the mail delivery vehicle stops to deliver your mail.
  2. The front of the mailbox must be located 6” to 8” back from the edge of the road surface.

If your curbside mailbox does not meet these USPS requirements, the mail person does not have to deliver your mail.

After considering the above, if the area where you want to place your mailbox post is grass, garden, or any other easily permeable material, an In-Ground Post will serve your needs. The In-Ground post is 43” long, so assuming the permeable surface is level with the road surface, the post should be buried 12” in the ground. This will ensure that the base of the incoming mail slot on the Mail Boss will fall within the USPS specifications summarized above.

If the permeable surface in which you will be burying the In-Ground post is higher than the road surface, you will need to bury the post deeper. To measure this, refer to the In-Ground Post Installation Instructions. Also refer to In-Ground installation instructions for multiple box installations on one post using our spreader plates, and for installation in certain climate conditions.

If the area you want to place your mailbox is cement (typically a sidewalk), you will need to use the Surface Mount Post and Base Plate combination. The Surface Mount Post comes with a Base Plate, and is only 27” because if you have to use the Surface Mount application, your mailbox will likely be mounted close to the edge of, or on, a 4” to 8” curb. The 27” Surface Mount Post and Base Plate combination places the incoming mail slot of your Mail Boss within the USPS installation requirements specified above.

If neither of these installation applications applies to you because you have some unusual circumstance, please Contact Us for advice.


  1. Gayle Makofsky on January 6, 2010 at 11:11 am

    There is obviously a lot to know about this. Thanks

  2. Jackline Slezak on March 15, 2015 at 5:17 pm

    We have an existing embedded and stable round post. Do you have any mechanism to mount to that or do we have to dig up old post and install a new square one to use your mail box?

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