DNS record configuration for a website with the mail server hosted on different server, domain (FQDN) and IP

Question

I am running into a problem which is as follows:

I have two domain names with different IPs;

The first is EXAMPLE.COM to host my website. Say the IP for EXAMPLE.COM is 111.111.11.11.

The second domain is an FQDN to host my email, say that it is MAIL.EXAMPLE2.io.

The DNS Console currently supports these record types on the graphical interface: A, AAAA, CNAME, MX, NS, SRV, TXT.

I want to add A record for MAIL.EXAMPLE2.io on the DNS of my website EXAMPLE.COM. But the website DNS has EXAMPLE.com by default with each A record I add.

For example, if I want to add the below:

# Name              Type       Value
mail                IN A       1.2.3.4

It will become like this:

# Name                            Type       Value
MAIL.EXAMPLE.IO.example.com         A       222.222.22.22

Or, I can add MAIL alone, and it will become MAIL.Example.COM.

How can I solve this problem where I enter the A record to become:

# Name                Type       Value
MAIL.EXAMPLE.IO         A       222.222.22.22

Cloudflare has a better DNS configuration, and it will resolve my problem, but I don't want to use it on this website.

To better illustrate what I see, please look at this image:

When I run sudo docker-compose logs --tail=200 -f acme-mailcow, I get these errors:

• Cannot match your IP 222.222.22.22 against hostname autodiscover.EXAMPLE.COM (DNS returned 111.111.11.11)
• Cannot match your IP 222.222.22.22 against hostname autoconfig.EXAMPLE.COM (DNS returned 111.111.11.11)

Update:
The purpose of this update is to answer questions I received in the comments and make them visible to everyone.

1. example2.io
   The DNS configuration for example2.io where I host my mailserver is below. This is inline with mailcow documentation: Note that the root directory of this website points to a different IP other than the mailserver (i.e., 333.333.33.33)
   
   
2. example.com
   The DNS configuration for the domain example.com where I want to host a website in the root directory is below. I want the emails of example.com to be handled through a mailserver hosted on mail.example2.io. To properly configure the mail on this domain, I want to remove .example.com from the configuration. That was possible on cloudflare DNS configuration.
   
   
3. example3.com
   example3.com is a domain name that I have its DNS record configured through Cloudflare and its email is handled through the mailserver example2.io. The DNS record configuration of this domain is below and this is how I am trying to configure example.com.

Answer 1

It sounds like what you really want is to have mail.example.com resolve to the IP address of mail.example2.io. To do this, add a record of type CNAME, with mail as the name, and mail.example2.io as the value. mail.example.com would then resolve to 222.222.222.222. This is exactly how the autoconfig and autodiscover records shown in your screenshot have been configured.

You can't add a record with mail.example2.io as the FQDN to the DNS zone example.com, as such a record could not be part of that zone. I can promise you that Cloudflare would not let you do this either.