PHP - Moved: Spamming Me

I have done lots of research on this, and I am trying out numerous method to counter this, which includes using mail() function with various arguments for the header, the PHPMailer class libraries and including a TXT file in my DNS settings with Godaddy.  as far as mail() is concerned, I have this code:

if( empty($errors))
{
    $to = '$myemail';
    $email_subject = "Customer Contact Request Submitted";
    $email_body = "A potential customer has sent you their contact information:\r\n\r\n" .
    	"Name: " . $firstname . " " . $lastname . "\r\n" . 
    	"Email: ". $email . "\r\n" . 
    	"Phone: " . $phone . "\r\n" . 
    	"Products Interested In: " . $products_interested_in . "\r\n" . 
    	"Message: " . $message;
    $headers = "From: no-reply@domain.com\r\nReply-To: $email\r\nReturn-Path: $email\r\n";
    mail($myemail, $email_subject, $email_body, $headers);

    echo "Your contact information has been sent.  A respresentative will contact you shortly.";
} else {
	echo $errors;
	   }

and the message is sent fine, but gmail spams it out every time it's sent regardless of whether it is marked as "not spam" and moved to the inbox.  I have not read anything on what can be put in the header argument to try and prevent the spamming out.   thoughts anyone?   Secondly, I have not yet written the code to call PHPMailer class libraries, but all the experts say it is the most reliable way to send mail.  Is PHPMailer messages known to be spammed out too?   Thirdly, the TXT file I put in my DNS reads the following, per response #2 on this page: https://stackoverflow.com/questions/43241773/prevent-php-mail-sent-going-to-spam-gmail

Type: TXT
Host: mydomain.com
Value: v=spf1 ip4:myIPaddressHere ~all
TTL: Automatic (Godaddy's option for Automatic is "1 hour")

I have to wait another 24 hours to see if that will fix the spamming issue.  Godaddy requires 48 hours for their server to adopt the new settings.  Does this look right to you guys as well?  thanks.