The Mexican postal system is notoriously slow and unreliable; letters usually arrive in one piece (albeit late), but never send packages through the postal service or expect to receive them, as they may be stolen. Instead, use a courier service or MexPost, the more reliable branch of the Mexican Postal Service.
Post offices (oficinas de correos) are found in even the smallest villages. International postal service is all airmail, but even, so your letter will take anywhere from 10 days to six weeks to arrive. Service within Mexico can be equally slow. It costs 10.5 pesos (about 70¢) to send a postcard or letter weighing under 20 grams to the United States or Canada; it's 13 pesos ($1.17) to Europe and 14.5 pesos ($1.30) to Australia and New Zealand.
Correos (Calle Colombia 1014, El Centro, Puerto Vallarta, 48300. 322/222–6308. www.sepomex.gob.mx.)
FedEx, DHL, Estafeta, and United Parcel Service are available in major cities and many resort areas (though PV doesn't have a FedEx office). It's best to send all packages using one of these services. These companies offer office or hotel pickup with 24-hour advance notice (sometimes less, depending on when you call) and are very reliable. From Puerto Vallarta to large U.S. cities, for example, the minimum charge is around $30 for an envelope weighing ½ pound or less.
DHL (Bd. Francisco M. Ascencio 1046, Zona Hotelera Sur, Puerto Vallarta, 48330. 322/222–4720 or 01800/765–6345. www.dhl.com.)
Estafeta (Libramiento Luis Donaldo Colosio 122-B, Zona Hotelera, Puerto Vallarta, 48330. 322/223–2700 or 322/223–2898. www.estafeta.com.)
Mail Boxes Etc. (Calle Ignacio L. Vallarta 130, Local 3, Zona Hotelera Norte [Col. Versalles], Puerto Vallarta, 48333. 322/222–2252. www.facebook.com/MailBoxes.Etc.PV.)