Amex: PO Box 30384, Salt Lake City, UT 84130-0384

For the time being, we know that there are two kinds of situations:
The big envelope is the Amex Savings Account, which is discreet and as many as 45 pages. Don't ask me how I know that!!!!
The other regular envelopes are for notification type letters, e.g., change of agreement, application canceled, etc.

For reference only, feel free to add!