As long as you kept it in the freezer until shipping it is okay to use no matter how old it is. I would prefer an ounce of breast milk. I can work with less though. Donor milk is available as well.
You can ship it priority mail through the USPS in an envelope. The cost from El Paso to me is $6.70. You may want to double bag the milk if it has been stored in the freezer(Especially Medela bags!)
2131 Watson Springs Rd. Watkinsville, GA 30677
If you are local to Athens or Watkinsville you can arrange drop-off at the Mother Center Tuesday and Friday mornings or in Watkisnville evenings.