how to properly setup SPF in a clustered environment, using a frontend and a backend mailbox solution

I am trying to setup Sender's Policy Framework (SPF) on my exchange 2003 SP2 servers, in a clustered environment, using a frontend and a backend mailbox solution.  I am not sure it is configured right.  When I follow the instructions as outlined in an article, to configure the Froned exchange server:

http://blogs.technet.com/industry_insiders/articles/spf_in_sp2_exchange.aspx 

I get an error that states" Sender ID Filter must be configured globally on the the message delivery property pages.  Go to the message delivery object's property pages under Global Settings to configure Sender ID Filtering"

In the Sender IT Filtering tab of the Message Delivery Properties, I have it set to Accept(SenderID status will be attached to the message for further anti-spam processing.

any ideas?
SPF-error-screen-shots.doc
Kendall900Asked:
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Stacy SpearConnect With a Mentor President/Principal ConsultantCommented:
It would cause some, but I doubt massive amounts. Why? Its because they are usually using spoofed addresses that are legitimate. The NDRs you get will be from the fake addresses bouncing back to the admin box.

SPF is good to stop some spam, but not the best solution. I would recommend using IronPort devices if you can afford it $$$$$. If not Postini is a good alternative for smaller companies, followed by Barracuda Networks' devices.

Due to SPF not being implemented heavily globally, it only gets you so far in its effectiveness against spam. Even if it was, it still could be affected by a DNS poison attack where the after DNS is corrupted (which is a nightmarish situation) spam mail could be successfully sent through the SPF protection wall.
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Stacy SpearPresident/Principal ConsultantCommented:
Thats just a warning box telling you that the checkbox doesn't configure SPF filtering. Are you having issues with the filtering?
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Kendall900Author Commented:
Yes it appears that the SPF is not doing reverse name look up since I am still getting SPAM from addresses that I know does not exist.
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Stacy SpearPresident/Principal ConsultantCommented:
You are in accept mode according to your screenshots. That means that Exchange will still accept and deliver the message.

What you might need is a SMTP Sink that scans the inbound message for a failed SPF status and moves it to an admin folder or somewhere for intervention.

Or you could Delete or Reject the messages. Reject is the best as sending parties can at least dispute their failures with you whereas delete doesn't tell them anything.
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Kendall900Author Commented:
but wouldn't that cause a massive amount of NDR since the spammers do not have valid addresses, as such the NDR's would be stuck in my queue
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