Does eltham nationwide haveane mail address
According to the New Zealand Post website, the Eltham PostShop (Nationwide) does have a physical address:
Eltham PostShop Cnr High Street & Rangitikei Street Eltham 4625
However, it's worth noting that Eltham PostShop is a physical location and does not have a PO Box address. If you need to send mail to the postshop, you can use the above physical address.
If you're looking to send mail to a specific person or department within the postshop, you may want to contact them directly to ask for their specific address or contact details.