Thanks @Jesse Norell . Added lets see the results. Just to verify things about this client . He is only hosting the website on our server. DNS is from his domain provider and email is a microsoft exchange server he manages directly also. No sure if this have any value
You only see them in queue, if the first delivery attempt was not successful, than you have already been blocked by the other side. Maybe no new mails were sent. More probably it is in the wrong file. If you are using php-fpm (what you should do), then the file is in /etc/php/7.0/fpm/php.ini If you are using php7.3 or something else, it in the corresponding folder. Also you have to restart apache / php-fpm to read in the new file. Best thing is to add it in ispconfig to the website (options -> php settings)
Done and restart apache /php-fpm. All the spam mails are being sent to email ID's of the following 3 domains: web.de btinternet.com comcast.net Is there a way i can make postfix block email from being sent to these above domains
You should be able to change smtpd_recipient_restrictions to do that; you'll need to add an access map ahead of 'permit_mynetworks' (which is currently the first item) to be effective for localhost connections.
