I originally posted this in the 2000 exchange forum, although I've just found out it actually 2003 exchange cluster.
This was put to me by a customer, I dont know anything about exchange cluster or spam relay checking , but think this may be a configuration issue.
An email sent to certain ISP's gets queried to see if the sender is a relay, the cluster replies to this query via a different IP address.
So in a bit more detail outgoing email comes from the cluster IP address, this is NATed via the firewall to a specific outside address. The source IP address is queried by the ISP, but the response to that query comes from one of the individual servers within the cluster. So the firewall NAT's that address to the outgoing PAT address.
The ISP gets the reply orginating from a differnet IP address, so drops the email.
Question is how can they change the cluster to respond to the query with the cluster address?
Andy
This was put to me by a customer, I dont know anything about exchange cluster or spam relay checking , but think this may be a configuration issue.
An email sent to certain ISP's gets queried to see if the sender is a relay, the cluster replies to this query via a different IP address.
So in a bit more detail outgoing email comes from the cluster IP address, this is NATed via the firewall to a specific outside address. The source IP address is queried by the ISP, but the response to that query comes from one of the individual servers within the cluster. So the firewall NAT's that address to the outgoing PAT address.
The ISP gets the reply orginating from a differnet IP address, so drops the email.
Question is how can they change the cluster to respond to the query with the cluster address?
Andy
