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Thread: Block IPs that Don't Resolve via Reverse DNS Lookup

  1. #1
    eatickets is offline Active Member
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    Default Block IPs that Don't Resolve via Reverse DNS Lookup

    I'm sure I'm not the only one who's tried to do this, but I've checked the forums and Google and couldn't find any instructions or documentation on this one: is there any way to tell Zimbra to block email from any IP address that doesn't resolve via a reverse DNS lookup?

    I'm running ZCS Version 6.0.14_GA_2928.NETWORK on Ubuntu 8.04.

  2. #2
    gvillaran is offline Loyal Member
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    I think there is a check button to do that in the MTA tab in Global Settings?

  3. #3
    eatickets is offline Active Member
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    Quote Originally Posted by gvillaran View Post
    I think there is a check button to do that in the MTA tab in Global Settings?
    I found a "DNS Settings" section. I'm assuming the setting you're thinking of is the check box for "Sender's domain (reject_unknown_sender_domain)"?

  4. #4
    gvillaran is offline Loyal Member
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    yes, thats the option i was thinking about.

    is that what you want?

  5. #5
    eatickets is offline Active Member
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    That's probably what I want, but I'm not entirely familiar with how the "reject_unknown_sender_domain" command works, so I want to make sure this will fulfill my original request before I implement it.

  6. #6
    gvillaran is offline Loyal Member
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    Well if i send an email from isme@mydomaindontexist.com it will be rejected if the domain "mydomaindontexist.com" doesnt exist.

    simple.

  7. #7
    eatickets is offline Active Member
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    But, is that the same thing as an IP address not resolving to a domain via reverse DNS lookup? It sounds like it is, but I want to make sure.

  8. #8
    eatickets is offline Active Member
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    Also, can anyone give me the likelihood of legitimate email being blocked with this reverse DNS lookup feature enabled?

  9. #9
    Yves Pires is offline Senior Member
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    bad mail server setup

  10. #10
    eatickets is offline Active Member
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    Quote Originally Posted by Yves Pires View Post
    bad mail server setup
    What do you mean by this?

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