How do I resolve this issue? Is this a problem?
Since I send thousands of emails a day, I'm worried my email server is being listed as spam.
I've tried adding a command to Postfix:
qq.com REJECT
but this doesn't affect anything.
I've also tried blocking the IP addresses of qq.com and mx3.qq.com with the ufw command, but this hasn't worked.
Please help if you've experienced this and have a solution. Thank you.