SUMMARY

To check whether the DNS entered in the SMTP options is valid and able to perform lookups, use the nslookup utility to check a domain.

DETAIL

If this fails, then MailEnable will not be able to send any email out to remote mail servers. If your DNS is not contactable, or invalid, the following errors are likely to appear in the SMTP Debug logs:

Message Delivery Failure. Attempt (1): Could not find mail server for domain (domain.com). The remote mail server could not be contacted at this time. Message has been requeued.
Error (1460): Could not resolve MX list for domain [domain.com]
SMTP Connection DNS Server could not resolve domain name (domain.com) in a timely fashion. Check DNS Server settings.