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  1. #1
    4 Star Lounger
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    Flood of Odd Undeliverable Messages (2000)

    For the past 2-3 weeks some users on our network have been receiving a steady stream of NDR undeliverable messages. It's clear from the subject line that the original email was spam and obviously not sent by any of our users. A message says the user can't be reached. The e-mail account does not exist. But that person who doesn't exist is the same person who supposedly sent the email and their e-mail address does most definitely exist. Another oddity is the fact there is no error code at the end of the message. Has anyone else been receiving something like this? How do I combat it? I can't just block all undeliverable messages.
    Daisy

  2. #2
    Plutonium Lounger
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    Re: Flood of Odd Undeliverable Messages (2000)

    If you have made sure that none of the computers on your network has been infected with software that sends out spam, there is little you can do about it, since it means that a computer outside your control is the culprit. You might try to trace the real sender, but that is usually fruitless. In many cases, the flood dries up after a few days.

  3. #3
    4 Star Lounger
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    Re: Flood of Odd Undeliverable Messages (2000)

    That's what I thought too but this has been going on for several weeks. Plus if someone was spoofing one of email addresses on spam, wouldn't the undeliverable message say it couldn't deliver the email to someone outside the organization? Rather, the message says it can't be delivered to the same person who supposedly sent the email because they don't exist, but they do exist. It's all very confusing.
    Daisy

  4. #4
    Plutonium Lounger
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    Re: Flood of Odd Undeliverable Messages (2000)

    I don't know how exactly spammers work, so I cannot explain the messages you get. But unless you can trace the e-mails to an ISP near you, there is little you can do about them, whatever the error message might mean.

  5. #5
    4 Star Lounger
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    Re: Flood of Odd Undeliverable Messages (2000)

    Yeah. I was just hoping someone else was having the same problem. Misery loves company. For now in the short term I have our keyword spam filter tagging and moving the messages to the quarantine folder so folks will stop getting them in their inboxes.
    Daisy

  6. #6
    Super Moderator jscher2000's Avatar
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    Re: Flood of Odd Undeliverable Messages (2000)

    I'm not sure how your virus filtering works, but non-delivery messages also have been used as a vector for delivering malware. If the message looks "fake," this might be the explanation.

  7. #7
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    Re: Flood of Odd Undeliverable Messages (2000)

    I've been getting the same flood for quite a while. Unfortunately, by default I'm the postmaster at work so I get a copy of all the NDRs. We get many, many NDRs for addresses that do not exist at the company. We also get some that are obviously spoofed and I just delete those. However, I can't just arbitrarily delete all the NDRs because a client or prospect may have mis-spelled a name and I can't trust that the sender will receive or read or understand an NDR on their end. We are about to migrate to a new server and Exchange 2007. I'm going to spend a litlle time then to see what I can do programatically to reduce the number I see.

    Joe
    Joe

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