5.5.4 Invalid Address

Hi Renzo! I have an SMTP Server without SSL / TLS but if I want to send an mail I always get this error. Im using an MEGA with ENC28J60 Shield. I used 0 / 0 as login because the Server doesnt need them. Here is my Code:

// Includes
#include <Arduino.h>
#include <EMailSender.h>
#include <IPAddress.h>

// Set Mail Params

EMailSender emailSend("0","0","test@test.com","SmartTest","IP of SMTP",25); // to be defined

//

byte mac[] = { 0xAA, 0xCD, 0xBE, 0xEF, 0xDD };

// the setup function runs once when you press reset or power the board

void setup() 
{
	// INIT
	Serial.begin(115200);

	Ethernet.init(53);
	Ethernet.begin(mac);

	Serial.println("IP: ");
	Serial.println(Ethernet.localIP());

	

	EMailSender::EMailMessage message;
	message.subject = "Test";
	message.message = "Bestanden!";

	EMailSender::Response resp = emailSend.send("smarttest@gmail.com", message);
	
	Serial.println(resp.status);
	Serial.println(resp.code);
	Serial.println(resp.desc);

}

// the loop function runs over and over again until power down or reset
void loop() {
  
}