lib/API.php
public function start_on_drip_campaign($recipient_address, $drip_campaign_id, $data=null, $args=null){
        $endpoint = "drip_campaigns/" . $drip_campaign_id . "/activate";

        $payload = array();
        if (is_array($recipient_address)) {
            $payload["recipient"] = $recipient_address;
        } else if (is_string($recipient_address)){
            $payload = array(
                "recipient_address" => $recipient_address
            );
        }

        if (is_array($data)) {
            $payload['email_data'] = $data;
        }

        if (is_array($args)) {
            $payload = array_merge($args, $payload);
        }

        return $this->api_request($endpoint, self::HTTP_POST, $payload);
    }
public function start_on_drip_campaign($recipient_address, $drip_campaign_id, $data=null, $args=null){
        $endpoint = "drip_campaigns/" . $drip_campaign_id . "/activate";

        $payload = array();
        if (is_array($recipient_address)) {
            $payload["recipient"] = $recipient_address;
        } else if (is_string($recipient_address)){
            $payload = array(
                "recipient_address" => $recipient_address
            );
        }

        if (is_array($data)) {
            $payload['email_data'] = $data;
        }

        if (is_array($args)) {
            $payload = array_merge($args, $payload);
        }

        return $this->api_request($endpoint, self::HTTP_POST, $payload);
    }
public function start_on_drip_campaign ( $ recipient_address , $ drip_campaign_id , $ data = null , $ args = null ) { $ endpoint = "drip_campaigns/" . $ drip_campaign_id . "/activate" ; $ payload = array ( ) ; if ( is_array ( $ recipient_address ) ) { $ payload [ "recipient" ] = $ recipient_address ; } else if ( is_string ( $ recipient_address ) ) { $ payload = array ( "recipient_address" => $ recipient_address ) ; } if ( is_array ( $ data ) ) { $ payload [ 'email_data' ] = $ data ; } if ( is_array ( $ args ) ) { $ payload = array_merge ( $ args , $ payload ) ; } return $ this -> api_request ( $ endpoint , self :: HTTP_POST , $ payload ) ; }
Start on drip campaign

The additional optional parameters for $args are as follows:
'sender' - Default is null. Array ("address", "name", "reply_to") of sender.
'cc' - Default is null. Array of ("address", "name") for carbon copy.
'bcc' - Default is null. Array of ("address", "name") for blind carbon copy.
'tags' - Default is null. Array of strings to tag email send with.
'esp' - Default is null. Value of ("esp_account": "esp_id")

@param array $recipient_address array of ("address", "name") to send to
@param string $drip_campaign_id drip campaign being added to
@param array (optional) $data email data being sent with drip
@param array (optional) $args additional options being sent with email (tags, cc's, etc)
@return array API response object
Start on drip campaign