If you were born in Manhattan, Brooklyn, Bronx, Queens, or Staten Island, and ordered a long form birth certificate specificatlly for foreign use, you will get a birth certificate with a Letter of Exemplification. 

A Letter of exemplification is a separate page attached to a New York City long form birth certificate. It is hand-signed by a Deputy City Registrar and attests that the attached birth certificate is a true copy of the actual record.

Exemplification letters can only be attached to the NYC long form birth certificates at the time a certified copy is issued. You cannot request a Letter of Exemplification separately. However, a long form birth certificate is acceptable for an apostille with or without a Letter of Exemplification, provided it is original and has a raised seal.

Where do I get a certified copy of the long form birth certificate with a Letter of exemplification?

If you were born within the five boroughs of New York City, you first option is to apply in person or mail the request to the New York City Department of Health and Mental Hygiene at 125 Worth Street, New York, NY, 10013.

When ordering, specify that you need the birth certificate for foreign use, then you will get a Letter of exemplification.

You will not be able to get a long form birth certificate over the counter. It will be mailed to you within two-three weeks. Short form birth certificates can be obtained over the counter.

Your second option is to use a private online service called VitalCheck that is the only agent authorized by the NYC Department of Health and Mental Hygiene to assist you with the retrieval of your birth certificate. When ordering, you must specify that the purpose of your request is APOSTILLE/AUTHENTICATION. Then, most likely, you will get your birth certificate woth a Letter of Exemplification. VitalCheck works OK, they also mail documents to foreign countries.

Is it true that an Exemplification letter is required in order to get a long form birth certificate legalized by an apostille or by a foreign embassy?

No, it is not true. New City birth certificates can be apostilled / legalized with or without an Exemplification letter.

Aso of now, a Letter of exemplification is not a must for the legalization purposes. If you received your birth certificate with a Letter of exemplification, wonderful! It will be legalized in accordance with the standard procedure, first by the County Clerk's office in New York City, and then by an apostille or foreign certificate / embassy. If however, your birth certificate came without a Letter of exemplification, do not despair! A different procedure will be used. Thankfully, there is a court in New York that can authenticate the signature of the City Registrar (present or former) directly, without a Letter of exemplification. After that, the document will be apostilled or legalized by a foreign embassy according to the standard procedure.

A few consulates (e.g. the Italian consulate) specifically require that you submit a long form birth certificate with a Letter of exemplification. Please follow the consulate requirements. However, if a Letter of exemplification is not specifically required (like in 99% of the cases), your birth certificate can be apostilled / legalized without it.