You can make a payment online anytime. Once you pay online, the payment will post to your account within 24-36 hours.
If you still prefer to mail a payment, you can send a payment by check or money order made payable to American Express. Please make sure to include your account number on the front of your payment.
First Class Mail
P.O. Box 650448
Dallas, TX 75265-0448
Attn: Express Mail Remittance Processing
20500 Belshaw Ave.
Carson, CA 90746