important emails from amex (about account, payment, address change, request replacement card, email change etc.) will always address you by name and last name.
No email from amex starts with "Dear Cardholder".
Marketing emails from amex (Platinum access benefits etc) will not address you at all.
I asked for a replacement card for my worn out charge card and got this email;
Just confirming your recent request
See your account Learn how to protect your Card
For your security:
Dear NAME LASTNAME,
We were recently asked to replace your American Express Card. While we´re in the process of sending your replacement Card, we wanted to make sure this request was made by you.
If you did ask for a new Card - or if you´ve already spoken with us about this matter - please feel free to delete this e-mail now.
If you did not make this request, please call the number on the back of your card or your billing statement today so we can ensure the safety of your account. For a list of phone numbers please click here.
The security of your account is our top priority.
Sincerely,
American Express Customer Service