My message is sent as spam

[Sic Laskie]

I have a contact form in my website, using the php below to delivery the form result as email.

<?php
if(!isset($_POST['send']))
{
    //Need to submit the form.
    echo "error; you need to submit the form!";
}
$name = $_POST['name'];
$visitor_email = $_POST['email'];
$message = $_POST['message'];

//Validate first.
if(empty($name)||empty($visitor_email)) 
{
    echo "Your Name and Email is required, please try again!";
    exit;
}

if(IsInjected($visitor_email))
{
    echo "Bad email value!";
    exit;
}

$email_from = 'silas@sicdesigns.info';//<== this websites email, I shall update this when we get the domain name.
$email_subject = "New Form Submission SiC";
$email_body = "You have received a new quick message from $name.\n\n".
    "Here is the message:\n
    From: $visitor_email\n\n
    $message\n\n".
    
$to = "sicdesigz@gmail.com";//<== where it will send the message to, let me use my email for now.
$headers = "From: $email_from \r\n";
$headers .= "Reply-To: $visitor_email \r\n";
//Send the email!
mail($to,$email_subject,$email_body,$headers);
//done. redirect to thank-you page.
header('Location: thank-you.html');


// Function to validate against any email injection attempts
function IsInjected($str)
{
  $injections = array('(\n+)',
              '(\r+)',
              '(\t+)',
              '(%0A+)',
              '(%0D+)',
              '(%08+)',
              '(%09+)'
              );
  $inject = join('|', $injections);
  $inject = "/$inject/i";
  if(preg_match($inject,$str))
    {
    return true;
  }
  else
    {
    return false;
  }
}
   
?>

My problem is that whenever someone uses the contact form, I receive the email as spam, instead of the normal inbox folder. Could the problem be in the php above?