A notarized letter is a typed or written correspondence to a person or organization that has been stamped or sealed by a notary. Doing so states the signature on the letter is legitimate.
A notary checks identification, watches a person sign the letter or document and then places a stamp near the signature. It is the notary's responsibility to ensure the person sending the letter is not doing so against his will. Any signs of distress or intoxication are considered to be red flags. The notary typically verifies the contents of the letter with the sender, so he knows what he is signing.