What are some common methods to prevent multiple emails from being sent in PHP?

To prevent multiple emails from being sent in PHP, one common method is to use a flag or a variable to keep track of whether an email has already been sent. This flag can be set after the email is sent and checked before sending another email. Another approach is to use a timestamp to limit the frequency of email sending, ensuring that a certain amount of time has passed before sending another email.

// Example using a flag to prevent multiple emails from being sent
$alreadySent = false;

if (!$alreadySent) {
    // Send email code here

    $alreadySent = true;
}