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Postmaster + NDR issue

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  • Postmaster + NDR issue

    Exchange 2003 STD edition, set-up as front end/ back-end.

    Installed by another company which originally had no postmaster mailbox. This was confirmed using dsquery and the account used to install exchange did not have the "copy ndr to" on the messaging tab either, although you could open it in outlook and see the test mail they had sent and received.

    If someone outside the domain sent mail to an unknown address, no ndr would be returned, although my understanding is this is the default for exchange (this was ticked when checked).

    When using the tracking tool via ESM, it states the ndr has been generated.

    A postmaster mailbox was created and the "copy ndr to" was completed, although the sender is still not receiving an ndr.

    So i have a few questions:

    Does all mail with no mailbox go no-where unless a "catch all" account is created as described here?

    What have i missed with regards to the sender not receiving an ndr?

    One of the forum members in this thread states that a third party solution is required for the original e-mail to be made useable.

    Is there a reason for this behaviour, or have Micrsoft done it for a purpose?

    Thanks for looking!

  • #2
    Re: Postmaster + NDR issue

    postmaster@ is usually on the account used to install Exchange. It isn't something that has to be created. Therefore I would suspect that the external people were given an account to use and then this account was deleted.
    Furthermore it doesn't have to be a specific account. I usually put postmaster@ on to the administrator account.

    Best practise is to enable recipient filtering and the tarpit. This means that the server does not accept the email message when it is addressed to a non-existent user. Your server will not generate the NDR, the server that is trying to send the email is forced to generate the NDR. This is more efficient as it means the sender gets an NDR immediately and it also means your server cannot be the subject of an NDR attack.

    Catch alls should be left where they belong - in the 1990s. They are nothing but a spam and virus trap and I would actually consider them a security risk.

    Simon Butler
    Exchange MVP

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    • #3
      Re: Postmaster + NDR issue


      Thank you for your reply. Makes perfect sense.