Sender Domain Selection and DNS Requirements

When multiple domains or subdomains are configured, the system selects the deepest configured subdomain as the sending domain.

For example, if an email is sent from example.com and only example.com is configured, the system uses example.com as the sending domain.

If both example.com and marketing.example.com are configured, the system uses marketing.example.com as the sending domain.

Each configured domain or subdomain must be configured separately in DNS. Subdomains do not automatically inherit DNS settings from their parent domain.