How to pay the bill via mail?

You also have a option of paying via mail. You can write a check or purchase money order which ever your prefer and then write the amount. Then include any coupon if used. Then mail the envelope and coupon to TJX Rewards Platinum Mastercard,PO Box 669819,Dallas, TX 75266-0773
TJX Rewards Credit Card, PO Box 669818, Dallas, TX 75266-0772.

Source: https://www.accountiod.com/tjmaxx-credit-card-login/