How can PHP developers improve their understanding of regular expressions and avoid common mistakes when using them for email validation and sanitization?

To improve their understanding of regular expressions and avoid common mistakes when using them for email validation and sanitization, PHP developers can refer to official documentation, practice with online tools like regex101.com, and test their expressions thoroughly before implementing them in their code.

$email = "example@example.com";

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    echo "Email is valid";
} else {
    echo "Email is not valid";
}