I administrate an email system for a commercial ISP. I'm currently having an issue with one of our customers relaying outbound SMTP traffic from their Exchange system through ours, and they're generating NDRs and other failure messages in response to spam. I need them to stop doing this, however their own admin is not very savvy. I'd rather provide them some guidance than leave them blocked from using our relays.

Having never worked with Exchange (I'm a *nix/BSD guy), is there some way they can accomplish this without other software or hardware in front of it? I've looked at the header content and they are scanning for spam, which is adding an X-* header which identifies the message as such. Can Exchange outbound filter this?

Does anyone have any other ideas on stopping these NDRs before they ever get to our servers?

  • 1
    I assume you mean NDRs and not DSN. DSNs are sent to users, NDRs would be sent to spammers. As well, would be a good idea to inquire the other sysadmin on which version of Exchange he's running. Based of this info, it would be possible to suggest the most accurate solution.
    – Vick Vega
    Apr 28 '11 at 19:53
  • Yes, NDRs, not DSNs :) Edited accordingly.
    – brent
    Apr 28 '11 at 19:57
  • Recipient Filtering - that's what will help you.
    – Vick Vega
    Apr 28 '11 at 20:19

I'm assuming you are talking about the NDR that is being fired off when they get spam or email sent to an invaild address. If they are running Exchange 2007, they can disable the sending of an NDR. Here is a link to do that.

  • Yes sorry, NDRs. I edited the question. So is there no way to leave NDRs enabled, but just make a decision about generating one based on say, the positive spam header?
    – brent
    Apr 28 '11 at 20:00

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