Hello, I'm using an external SMTP server I've configured as my send-only/don't reply email sender and I want to remove the following header in outlook: (No client certificate requested) To resolve this issue, adding the following commands to my postfix main.cf file requires that all clients present a certificate: ``` smtpd_tls_req_ccert=yes smtp_tls_req_ccert=yes ``` I cannot find any smtp settings to configure the smtp client to present the SSL certificate nginx has been configured to use as an ssl certificate. The options are available in PHPMailer as: ``` $mail->SMTPOptions = [ 'ssl' => [ 'verify_peer' => true, 'local_cert' => '/path/to/client_cert_and_key.pem' ] ]; ``` The snippet above was taken from the following StackOverflow Question: https://stackoverflow.com/questions/45453980/connect-to-smtp-server-with-client-certificate-without-password-from-php-scrip Further SSL Options for PHPMailer are: https://github.com/PHPMailer/PHPMailer/blob/master/examples/ssl_options.phps And additional postfix configuration information is at: http://www.postfix.org/postconf.5.html#smtpd_tls_req_ccert http://www.postfix.org/FORWARD_SECRECY_README.html The current configuration for gitlab produces the following warning in the postfix maillog: `NOQUEUE: abort: TLS from unknown[x.x.x.x]: No client certificate presented` Causing the confirmations, follow-ups and any emails to be not sent due to this. Are there any workarounds that do not involve removing the client certificate requirement for gitlab?