Hello Carly,

I have change "Lettermail" to "Regular Mail". Is that what you see "Regular Mail". Just look for "Regular Mail" in includes/modules/shipping/canadapost.php and change it to "Lettermail".

Code:
        case 'CA':
          {
            $table_cost = preg_split("[:,]", constant('MODULE_SHIPPING_CANADAPOST_LETTERMAIL_CAN'));
            $lettermail_service = sprintf("Regular Mail: estimated %d-%d business days", round($this->turnaround_time / 24 + 2), round($this->turnaround_time / 24 + 4)); //factor in turnaround time
            break;
          }
Change to:

Code:
        case 'CA':
          {
            $table_cost = preg_split("[:,]", constant('MODULE_SHIPPING_CANADAPOST_LETTERMAIL_CAN'));
            $lettermail_service = sprintf("Domestic Lettermail: estimated %d-%d business days", round($this->turnaround_time / 24 + 2), round($this->turnaround_time / 24 + 4)); //factor in turnaround time
            break;
          }