flame.org's qmail mods: Soft DNS Error

The address listed in the SMTP envelope's "MAIL FROM:" line had a temporary DNS failure. This can be caused by a number of reasons:

All DNS servers for the domain are overloaded, and the reply did not come in on time.
All DNS servers for the domain are unreachable.

In any case, this is marked as a temporary failure, so the mail should be retried by the sending SMTP host.