What does a notarized letter mean?
A notary is a US citizen who has taken special classes in legalizing documents. They stamp your document, which is called notarizing it, and that makes it a legally recognized document in the USA. It sounds like you live outside the USA. If you do, the only place you can have a letter notarized for the USA is a USA Embassy or Consulate. You need to go there with your child’s mother, with the letter, your child’s mother will sign it at the embassy or consulate, the notary will notarize her signature. If I were you I would also bring a translated copy of the child’s birth certificate for notarization as well. My consulate in my city has notarization hours; it’s something like every Tuesday from 8-12. The cost is about 20 dollars, or the equivalent in local currency. You need to check your consulates website and see if there are open hours or if you need an appointment. Sometimes appointments take months to get so take care of this quickly. Good luck!