Persistent SMTP connection in PHPMailer

Question

How to enable persistent SMTP connections in PHPMailer?

I will send many emails, so with persistent connections probably I will get performance gain.

Answer 1

We really don't care here if your server gets blacklisted, right? This is how to achieve what you want. Just set to true the SMTPKeepAlive property and after the bulk sending, call implicitly the SmtpClose() method.

$phpMailer = New PHPMailer();
$phpMailer->isSMTP();
$phpMailer->SMTPKeepAlive = true;

for ( ... ) {
    // Send your emails right away
    [ ... ]
}

$phpMailer->SmtpClose();

Answer 2

By optimising the sending of emails, you might open yourself up as being identified as spamming and so cause web servers to block your IP.

How many emails are you sending? It may be better to actually throttle emails sent rather than speed up.