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email being rejected

Posted on 2009-05-13
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Last Modified: 2013-11-30
Hello,

I'm having issues sending email to particular domains that are rejecting my email or just simply blocking it.  I searched to see if our ip address was blacklisted and found that it was with some dnsbl's.  We're not spamming at all and I've had to write letters to get our ip address removed.

Barracuda Central was one of the first to inform me of being blocked.  I was rejected by a recipient.  It was suggested that I block port 25 from within the network.  I  changed everyone's smtp port number to 587.

The IP address that is being blocked is being used by one of my servers.  I have a NAT configured and the private IP of the server is pointing to the public IP visa versa.  Each message that I've gotten from rejected email points to our public IP address.  

Can this be false alerts to dnsbl's?  I've had no problems up until a few days ago.  Nothing with our configurations has changed.  I have no rogue machines spamming email due to the fact that I've blocked port 25 internally.

I'm having issues sending email to certain domains.  One issue doesn't happen all the time; I have another issue of sending email to a domain that does not reject the message it just goes into cyber space.  I've called and talked to our email service provider and they state they need header information from the email, but the problem is I'm not getting rejected emails from this one particular incident.

Does anyone have a suggestion or a new direction to take to figure this issue out? It would be greatly appreciated.  In the mean time I'll be thinking and searching for an answer.

Thanks in advance,
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Question by:lemastass
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ratan_koduru earned 500 total points
ID: 24382085
Do you mean to say that you blocked port 25 from all the machines and you still got blocked by some domains?

Did you check if that block was a result of earlier problems?

We had a similar problem some time back. When you get blocked the first time, they wait for around a month to un-block you. We blocked port 25 from all machines except the email server.

Ratan Koduru


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by:lemastass
ID: 24403739
Yes I blocked port 25 from being used internally by all devices using my firewall.  At this moment I cannot send email to cox.net from our domain, but we can send email to every other domain.  I called Cox service and they stated that we're not blocked.  I called our email service provider and they stated that there's isn't a problem. The messages are hitting our email server and making its destination to Cox.  It all points back to Cox.  

I've also contacted all dnsbl's to request removal of our ip address.  I haven't heard back from any of them yet.
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