Load balancing SMTP in a way that doesn't hide the source IP address

Posted by makerofthings7 on Server Fault See other posts from Server Fault or by makerofthings7
Published on 2012-06-21T17:51:36Z Indexed on 2012/06/22 3:18 UTC
Read the original article Hit count: 481

Filed under:

smtp

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load-balancing

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nat

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netscaler

I need to load balance SMTP to handle some applications that don't know how to use MX records.

I set up a Netscaler using the TCP option on port 25 and now Exchange sees the source IP as that of the DMZ of the Netscaler for every connection, not the client.

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Obviously this prevents RBLs, Whitelists, and all other IP-based reputation to fail. It also make it impossible to whitelist a trusted IP for anonymous relay.

Question

How should I configure the NetScaler (or Windows Load Balancing) so that I can allow load balancing yet still maintain visibility of the source IP?

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