I just noticed how to set up the DNS record for the Email server on Cloudflare DNS.
It should be
I have my very own Email server, with IP address, a.b.c.d. It is powered by iRedmail.
In Cloudflare DNS. I should set it up like this.
1) Add an A record for this mail subdomain.
2) Add an MX record that points to the subdomain above.
I was doing it in the wrong way. Made it in
Then no email can be sent and received. When I use Thunderbird Email App to retrieve the emails, it shew