[Exim] SERVFAIL

Recently, one of our users sent a message to an address for which the
DNS returned SERVFAIL at that particular moment. Exim returned an
error status "451 Temporary local problem - please try later", and
the message was not not queued. Is there a way to make Exim queue the
message and use the normal retry rules? In the case mentioned the DNS
was repaired soon, so why make the user send the message again - this
should be Exim's task.
BTW, "local problem" did not make much sense to me, since it
definitely was a remote problem.

TIA
Peter Rindfuss