How can PHP guess the name of an SMTP server for sending emails without manual configuration?

PHP can guess the name of an SMTP server for sending emails by utilizing the DNS MX (Mail Exchange) records of the recipient's email domain. By querying the MX records, PHP can determine the SMTP server responsible for handling emails for that domain. This automated process eliminates the need for manual configuration and simplifies the email sending process. 

<?php
function getSMTPServer($recipientEmail) {
    list($user, $domain) = explode('@', $recipientEmail);
    $mxRecords = [];
    getmxrr($domain, $mxRecords);
    $smtpServer = $mxRecords[0];
    
    return $smtpServer;
}

$recipientEmail = 'example@example.com';
$smtpServer = getSMTPServer($recipientEmail);
echo 'SMTP Server for ' . $recipientEmail . ' is: ' . $smtpServer;
?>

Keywords

PHP SMTP email server auto-configuration

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