I understand, and I have mitigated some problems like this, adding in my hosts file the IP 10.0.0.3 to the mail.domain.com domain, however I have 10 VMs using the same service, I have done the same action in the 10VMs, my question is why does this happen? Why Pfsense has that behavior, if everything will work fine, I shouldn't do this, that is, there is a problem because this is a temporary solution, if everything will work fine I would not have to make any changes to my servers to add that data.
Thanks @johnpoz