Some clients are not able to send email to gmail. Using outlook with SSL and SPA the emails go through using roundcube it does not. My setup : i have domain example.com Created sub domain mail.example.com with ssl Setup roundcube IMAP to use ssl://mail.example.com SMTP to use tls://mail.example.com this works fine now for cert since i have crt in ../ssl/mail.example.com.crt i setup : $config['smtp_conn_options'] = array( 'ssl' => array( 'verify_peer' => true, 'verify_depth' => 3, 'cafile' => '../ssl/mail.example.com.crt', ), ); This gives me error SMTP Auth Error 220 in logs it looks like this : ERROR: STARTTLS failed () ERROR: Invalid response code received from server (-1) ERROR: Invalid response code received from server (-1) Any help ?
CA = certificate authority, but you set that to the certificate file itself; is this a self signed certificate? If so, try setting 'allow_self_signed' => true
The certificate file with your server's letsencrypt certificate does not contain the CA certificate nor intermediary certificates; try setting cafile to /etc/ssl/certs/ca-certificates.crt (or wherever your system puts it, that works for debian/ubuntu).
