I got this one - Open close sensor....
https://smile.amazon.com/gp/product/B0118RQW3W/ref=pe_385040_215884960_pd_te_s_gc_ti/164-2669327-9202902?_encoding=UTF8&pd_rd_i=B0118RQW3W&pd_rd_r=WQRSKQZVYPN1WE0D03KZ&pd_rd_w=cnDQV&pd_rd_wg=XUvKj
edit and this is the mailbox
https://smile.amazon.com/gp/product/B008HVH502/ref=oh_aui_search_detailpage?ie=UTF8&psc=1