Spam firewall in inbound only mode ends up on DNS blacklists, how?

Posted on 2008-11-14
Last Modified: 2012-05-05
Hi, the title pretty much says it all. We have a Barracuda Spam Firewall 400 in INBOUND mode only. It is not passing any outbound mail. However somehow, as of this morning, it has ended up on the CBL, Spamhaus, and Barracuda Networks blacklists. Can someone explain to me how this is even possible?

Question by:Ivrnet
    LVL 10

    Expert Comment

    They should tell you why you are on the list if you query your domain name against them. My immediate reaction was a lack of reverse DNS which is something they complain about

    Author Comment

    Well, I already called Barracuda and they're looking into it for me.

    However, what does reverse DNS have to do with an inbound spam firewall? Nothing is being sent out through it.
    LVL 10

    Accepted Solution

    If the MX record of your domain points to that device as your inbound mail server it is meant to respond to reverse DNS queries... if it doesn't then spamhaus and the like bitch about it. (as it may imply a 'dodgy' server)

    Author Comment

    Hmm, I see. Okay, well we'll see what Barracuda says. Thanks.

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