What are the best practices for avoiding duplicate emails when sending newsletters through PHP?

When sending newsletters through PHP, one common issue is sending duplicate emails to the same recipient. To avoid this, you can maintain a list of email addresses that have already received the newsletter and check against this list before sending each email. 

// Check if email address has already received the newsletter
$recipient_email = 'example@example.com';
$newsletter_sent_list = ['example@example.com', 'another@example.com'];

if (!in_array($recipient_email, $newsletter_sent_list)) {
    // Send the newsletter email
    // Your code to send the email goes here

    // Add the email address to the list of recipients
    $newsletter_sent_list[] = $recipient_email;
}

Keywords

PHP newsletters duplicate emails email validation database normalization

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