On Jul 28, 2006, at 8:35 AM, Davis, Larry wrote:
I have a customer sending out more and more email notifications to
their clients from our VM system, which does not have an entry in
the Internet DNS system.
The user is currently using the SENDFILE command with the SMTP option.
The email is rejected as spam from the client end, because the
reverse DNS lookup fails for node.domain.com, but domain.com does
exist on the internet.
Well, the quick and correct solution is to add forward and reverse
DNS resolution for the VM system.
Failing that (or if you're behind NAT, in which case you have a layer
doing port translation anyway), throw a port redirector in front of
the VM system redirecting outbound port 25 from it to a system that
scans and relays outbound mail from your other machines, which
presumably will have been set up to act like a nice network citizen
and have correct DNS/RDNS entries. You almost certainly have one of
these in your organization anyway (or at least you block port 25 from
most addresses) because otherwise you would be on everyone's spam
blacklist as client Windows machines get infected--which they do,
because people just can't resist the urge to click on something that
promises them a glimpse of Anna Kournikova's naughty bits--and begin
spewing spam into the network.
Adam
