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Received: from unknown

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Can someone help me with this?

I cannot send an e-mail to a supplier of mine, this is the error I get!


Remote host said: 550 5.7.1 <xxxx[at]xxxx.com>... H:MXB [] Connection refused due to abuse. Please contact your E-mail provider.


Received: (qmail 32606 invoked from network); 6 May 2008 12:24:11 -0400

Received: from unknown (HELO plguide-win) (

by mail.plguide.com with SMTP; 6 May 2008 12:24:11 -0400


Please help!


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Wow, that has to be near the top of the list of useless bounce messages, the mail admin that set that up should be hit with a clue-by-four... Well, I suppose at least it did provide the IP address of the connecting server. A quick RBL check shows that is not listed with any of the major RBLs at this time. Its SenderBase numbers look reasonable for a dedicated MX, and its reputation is Good.

I suspect that this is either a manual filter setup by the recipients ISP, they are using some kind of Bayesian filtering, or they are using some obscure RBL somewhere that I didn't check. Either way, I would suggest attempting to contact the ISP directly to find out.

The receiving mail server doesn't seem to have identified itself anywhere in the error you posted, but when all else fails, you might try postmaster[at]<originalrecipientsdomain>.com. Technically postmaster addresses should bypass this kind of filtering, per RFC requirements. Unfortunately, this is not always the case. If you post the domain name you were sending to (no need to post the username portion of the email address, just the domain), I or someone else here can try to look up better contact information for you.

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Probably a "backscatter" case. I have read it from somewhere but the case was too serious. Like 100 bounce e-mails. Another new face in the world of spamming.

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