Sending via Amazon SMTP Error: Duplicate header ‘MIME-Version’

Hi John,

Thanks for reporting the issue. This seems to be a bug within the plugin and I’ve passed this issue to our development team and we will be investigating soon.

Have a good one!

Can you provide an update on this issue?

To my understanding WP Mail SMTP is supposed to overwrite/correct the headers. I have other plugins that create duplicate MIME-Version headers and AWS SES is refusing to send these as well.

• This reply was modified 5 years, 5 months ago by breeakpoint.

I have fixed the issue with the following code in my function.php

/*
  PHPMailer inserts the below custom headers so we must remove them as it creates
  duplicate issues with AWS SES. WP potential fix of issue will come with 5.3.
  https://core.trac.www.ads-software.com/ticket/43542
*/
add_action('phpmailer_init', 'phpmailer_init_fix');
function phpmailer_init_fix($mailer) {
    $headers = $mailer->getCustomHeaders();
    $mailer->clearCustomHeaders();
    foreach ($headers as $key => $header) {
        if ($key !== 'MIME-Version' && $key !== 'X-Mailer' ) {
            $mailer->addCustomHeader($key, $header);
        }
    }
}

Hi @breeakpoint,

Glad to know you sorted this out! We are investigating the issue as the error occurs only on certain server configurations. Hopefully, this will get fixed soon.

Have a good one! ??

No worries, I did’nt mention it in my post but a comment in my code. It is an issue with core WordPress that should be fixed in v5.3 (but I have not confirmed if it was as I have not upgraded yet)

Hi @breeakpoint,

Thanks for the information. We are not aware of any issue with the WordPress core. Please let us know after confirmation.

Thanks!

yeah here is the ticket https://core.trac.www.ads-software.com/ticket/43542