What are some best practices for ensuring emails sent via PHP are delivered correctly and do not trigger spam filters?

When sending emails via PHP, it's important to follow best practices to ensure they are delivered correctly and do not trigger spam filters. One way to achieve this is by setting up proper email headers, including a valid "From" address, a relevant "Subject" line, and a text/plain content type. Additionally, using a reputable SMTP server to send emails can also help improve deliverability.

$to = "recipient@example.com";
$subject = "Your Subject Here";
$message = "Your message here";

$headers = "From: yourname@example.com\r\n";
$headers .= "Reply-To: yourname@example.com\r\n";
$headers .= "Content-type: text/plain\r\n";

mail($to, $subject, $message, $headers);