How do we associate Amex on our accounts? Leroy Esterhuizen August 11, 2021 05:54 Updated Follow Once a merchant receives a merchant number from Amex they would need to send it to email@example.com, and request the Amex merchant number to be associated to their account. Related articles Who do I contact to apply for an American Express Merchant Account? How do I become a 3D secure merchant? Amex Safekey Comments 0 comments Article is closed for comments.