My experience in creating new domains is that the primary IP address is always selected as the domain's IP address.
When creating domains, you should always select the proper IP address.
Additionally, if you have IPV6 IP addresses you are specifically using for domains, the IPV6 selection should be set to DISABLED on both the domain and the SMTP out.
If you have an IPV6 IP address enabled, and do not have at least one of your primary server's FQDNs reverse mapped to it, you could end up with non-delivery issues because of being perceived as sending spam.
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