How many letters of St. Ignatius of Antioch are considered genuine?

There are seven letters of St. Ignatius of Antioch that are commonly held to be genuine.1

While these letters were known to Eusebius in antiquity, they were later corrupted by heavy interpolations and the addition of six forged letters. This enlarged collection was widely circulated during the Middle Ages. However, 17th-century scholarship successfully restored the original collection, allowing for a more objective historical assessment of his personality and theological views.12