I'm building a Sarge machine to replace a Woody, and I can't persuade
exim4 to do host lookups. All attempts at sending outgoing mail fail
with:
R=dnslookup defer (-1): host lookup did not complete.
Running exim4 -d -bt says that DNS lookup of abc.de (MX) gave TRY_AGAIN.
All other programs (as far as I can see) have no trouble using DNS. The
Woody machine running exim3, using the same local DNS cache, has no
problems.
I vaguely recall having similar problems with exim3 long ago, which I
think were solved by removing bydns from the remote smtp configuration,
but exim4 doesn't seem to have that to begin with.
All of the exim4 configuration files are original,
update-exim4.cof.conf is set for Internet use.