สงสัยว่า PHPMailer ทำไมถึงส่งได้เฉพาะอีเมล์ภายในบริษัท แต่ถ้าเป็นอีเมล์ภายนอก (gmail,hotmail) ทำไมจึงส่งไม่ได้ ครับ

// Function PHPMailer
  $mail1 = new PHPMailer();
  $mail1->CharSet = "utf-8";  
  $mail1->IsSMTP();
  $mail1->SMTPDebug = 0;
  $mail1->SMTPAuth = false;
  $mail1->Host = "10.x.x.x"; 
  $mail1->Port = 25;
  $mail1->Username = " "; 
  $mail1->Password = " ";
  
  $mail1->" ");  
  $mail1->" "); 
  $mail1->Subject = " "; 
  $body1 = " ";
                          
  $mail1->$body1);
  $mail1->$email); 

  if(!$mail1->Send()) {
      echo "Mailer Error: " . $mail1->ErrorInfo;
  } else {
      echo "Message sent Mail";
  $mail1->MsgHTML($body1);
  $mail1->AddAddress(....); 

  if(!$mail1->Send()) {
      echo "Mailer Error: " . $mail1->ErrorInfo;
  } else {
      //echo "Message sent Mail";
  }