If you're using a mail domain with SMTP Redirection and a hostname destination, this tool will automatically update the destination as an IP address or switch to "Accept and Hold" based on the results of the DNS lookup. This is useful for Dynamic DNS hosts, hosts that may occasionally withdraw their type "A" record, or hosts with unreliable DNS.
When Postfix (which we use) receives a negative answer from a DNS server for a domain used in SMTP Redirection (a Postfix transport map), it will return a fatal error. This is expected behavior because the DNS lookup returned a negative response (opposed to a lookup failure where no answer was available), however, in practice this is undesirable for some sites. Our IP address helper tool solves the problem by taking the DNS lookup away from Postfix.
To use the IP address helper feature, see:
To learn more about IP address helpers, see the documentation: