panyoet
Hi, check if SPF DKIM SSL is set. Check whether the reverse resolution of ip is set up. The reverse resolution of ip requires the server provider or network provider to help you set
Try to modify the configuration in the Config of postfix in the Service Status interface of the mail server management interface
Put: smtpd_tls_chain_files=/etc/ssl/private/ssl-cert-snakeoil.key,/etc/ssl/certs/ssl-cert-snakeoil.pem
Change to: smtpd_tls_chain_files = /www/server/panel/plugin/mail_sys/cert/135mailtest.com/privkey.pem,/www/server/panel/plugin/mail_sys/cert/135mailtest.com/fullchain.pem
Note to replace 135mailtest.com with your domain name.
Also check /www/server/panel/plugin/mail_sys/cert/135mailtest.com/ for privkey.pem and fullchain.pem files