NDR consider this message to be spam
Recently my users started to get several NDR's saying "consider this message to be spam". The NDR looks like this: Generating server: mymailserver.company.com customer@customer.com #< #5.5.0 smtp;552 Unable to process message: msg.1283184588.930408.20880 - error: recipient: customer@customer.com failed, reason: consider the message to be spam> #SMTP# Anyone have any ideas?
August 30th, 2010 7:41pm

That isn't a standard message, so will be generated by some kind of antispam application/appliance. You will need to contact the recipients company to find out what it is. Simon.Simon Butler, Exchange MVP. http://blog.sembee.co.uk , http://exbpa.com/
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August 31st, 2010 12:50am

If you get those NDR's from several destinations and from a specific domain, then check if you have PTR and also check if your IP got into a black list (http://www.mxtoolbox.com/blacklists.aspx) If you are in a black list, check your network for worms and malware to see if something is sending spam from inside your network.Yanir Ben-Nun / System Team Leader / IT / IS Professional
August 31st, 2010 9:48am

Hi, From the NDR, we can know the NDR was generated by your Exchange server. This means the message was refused on the SMTP session, so you should ensure your Exchange server is not in the blacklist. Then the destination server doens't add your email in the block list. Thanks Allen
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September 2nd, 2010 9:50am

I ran the blacklist check on the link above (i usually do this once a month). My server seems ok. From what i can see its my local server that denies my user to send the e-mail.
September 2nd, 2010 11:55am

You have made the common mistake of presuming it is your server because of the NDR. The NDR only tells you which server generated the message. It does NOT say which server ejected the message. Your server attempted to deliver the message to the next server, it rejected it at the point of delivery, forcing your server to generate the NDR. If you have checked the public blacklists then they are probably using something internal. You will need to contact them to find out what it is. Simon.Simon Butler, Exchange MVP. http://blog.sembee.co.uk , http://exbpa.com/
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September 2nd, 2010 12:51pm

I've done some more testing now. For example if i send e-mails to that domain, they come through fine. But if this other user (in my company) does, they bounce back, with the above NDR.
September 2nd, 2010 5:55pm

did you check for PTR? are you using a smart host to deliver or direct DNS?Yanir Ben-Nun / System Team Leader / IT / IS Professional
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September 2nd, 2010 8:08pm

I've done some more testing now. For example if i send e-mails to that domain, they come through fine. But if this other user (in my company) does, they bounce back, with the above NDR. That would tend to point to a content issue rather than a host based issue. However you will not get to the bottom of the problem without speaking to the recipients to see why they are flagging the messages as spam. This is not an Exchange issue per-se. It could be DNS related, but if that was the case I would expect a different NDR and it to affect all email. The NDR that is being returned is not very helpful unfortuantely. Simon.Simon Butler, Exchange MVP. http://blog.sembee.co.uk , http://exbpa.com/
September 3rd, 2010 2:54am

Hi, Is the smarhost deployed in the environment? Did you use the smarthost to send the email? Thanks Allen
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September 3rd, 2010 6:34am

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