Quick Answer

Use PHPMailer or Symfony Mailer for robust sending.

Understanding the Issue

The native mail() function has limitations. Libraries handle SMTP, attachments, and HTML content more reliably.

The Problem

This code demonstrates the issue:

Php Error 
// Problem: Basic mail()
mail($to, $subject, $message); // Often fails/spams

The Solution

Here's the corrected code:

Php Fixed 
// Solution: PHPMailer example
$mail = new PHPMailer();
$mail->isSMTP();
$mail->Host = "smtp.example.com";
$mail->setFrom("noreply@domain.com");
$mail->addAddress($to);
$mail->Subject = $subject;
$mail->Body = $htmlContent;
$mail->send();

Key Takeaways

Always use dedicated libraries for email.