Will this work with mailbox sold at Lowe’s - Item # 965125 Model # 8710RZ-10 Architectural Mailboxes 6.61-in W x 20.83-in H Metal Oil Rubbed B

The demensions given on the page appear to be incorrectly stated. Probably the dimensions are Length/depth 20.83, wide 6.61 and height 8.82. One would need to check with the supplier. If this is indeed the case then the mailbox post is a good fit.