We're playing around with Cyren on our primary mail server and it seems to be working pretty well, and catching most of the other 3% of mail SM doesn't think it'll catch. We have a backup mx server in a different data center that was previously setup to do its own spam scanning and pass the score to the main server. However, since we're licensing Cyren (well, currently in a trial) on our main server and I'd rather not pay for it twice, I'd like the backup MX to no long do anything with spam, pass everything to the primary server, and have it (and Cyren) do the spam scanning. How would we go about setting that up?
We currently have the spam settings config'd on the backup mx to "take no action" and the IP address of the backup mx is added in the bypass gateway section of the primary server. The backup MX is config'd to do user verification through web services against the primary server currently.