Fiji has post offices scattered throughout the country, with Nadi and Suva being the main hubs. Delivery is usually reliable, although service can be painfully slow. Surface mail tends to be the cheapest, but its arrival is prolonged and unpredictable. Airmail to New Zealand or Australia usually takes about three days, and to Europe or America it's about a week. It's possible to receive mail in all major post offices, and mail can be held for two months without charge. It's also possible to send and receive faxes at major post offices. Often, top-scale resorts and hotels offer postal services, so check with the front desk to see if they can help you.
Shipping packages and purchases to and from Fiji can be an adventure. FedEx operates in Fiji and is usually the safest bet. Some stores will offer to ship purchases home for you, but use your judgment: if the process seems smooth, chances are the store does this often. If forms can't be found, or there seems to be complications or questions, best to deal with the post office, FedEx, or even your accommodation host.
Post Fiji (www.postfiji.com.fj.)