Mount your Architectural Mailbox or other box safely atop the Architectural Mailboxes 46.5 in. Standard In-ground Post. This galvanized steel in-ground post is equipped with a large support plate and capable of holding single or multiple mailboxes with a spreader bar.About Architectural MailboxesBased in California, Architectural Mailboxes is the net result of two dedicated designers putting their heads together to create a superior product. Vanessa Taylor and Chris Farentinos are in charge, creating high-quality USPS-approved mailboxes with curb appeal that matches their functionality. You'll find top-notch materials, unique colors and finishes, and both traditional and new designs.