Private IP address Blacklisted for Email

Posted on 2011-02-18
Last Modified: 2012-06-21
        I seem to be having a problem with Blacklist and my Exchange Server.  It seems that my emails being sent out to certain domains are being blocked because the Private IP of the exchange server is blacklisted.  Here is my setup

Exchange 2003 server with a Private IP of
SonicWall NSA2400 Firewall with a Public IP of 173.25.38.xx

Message from Email Bounce Back

554 Service unavailable; Client host [] blocked using Barracuda Reputation;

I have searched for an answer now for some time, but have no luck.  Any help would be appreciated.
Question by:jdesesa-ITW
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Expert Comment

ID: 34930505 is not a private address. That is an address from Argentina; it's likly someone is spamming from this address and you've used this address inside your network.

Refer to this site for private address ranges:
LVL 32

Expert Comment

ID: 34930519 is not a private IP address.

It's public, and belongs in the LACNIC range (Latin America - Caribbean).

Telefonica de Argentina (

What makes you think that you can use that as a private IP address?
LVL 32

Expert Comment

ID: 34930533
^ pichford beat me to it.

There are thousands of spam reports against that IP address.  Most likely it is from any number of infected computers using that ISP's block of addresses.

Regardless, you should stick to the acceptable private IP addresses.  Not only will it avoid blacklist matches, but also avoid problems with flagging as a spoofed address.
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Expert Comment

ID: 34930548
Better type faster. =)

Technically speaking, you can use you address in the world you want; but if you attempted to access any services from that IP range it would fail. You could set your private address as; but you wouldn't be able to access Experts Exchange because it would look to your inside network. I only use private addresses internally; even in my private WAN network.

That's the curren IP address of by the way.

Best of luck chaps!
LVL 76

Accepted Solution

Alan Hardisty earned 250 total points
ID: 34932322
Please have a read of my article about problems sending mail to one or more external domains:

Author Comment

ID: 34933403
I understand what everyone is saying about using private IP addresses inside my LAN, however this was already in place when I took over from the previous IT manager.  If there is no other way, then I will have to change the internal network to a more appropriate private ip range.  I was hoping that there was a way of making the email look like it was coming from my Router External Address instead of the "Private" IP address of the server
LVL 76

Expert Comment

by:Alan Hardisty
ID: 34933553
Email originates from a server not a router, so whatever you try to do to disguise this will be in vain because the headers will always show the internal server IP of the sending server on your network and there is nothing you can do about it.

Expert Comment

ID: 34934567
You can always change your IP address. Our public IP was blacklisted once. I just changed the address by 1 number.. wasn't listed anymore. You can try that as a temp fix but you need to work on that addressing scheme. Best of luck.
LVL 74

Expert Comment

by:Glen Knight
ID: 35308299
This question has been classified as abandoned and is being closed as part of the Cleanup Program. See my comment at the end of the question for more details.

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