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  1. #1

    550 User Unknown -- Exchange 2000

    Exchange 2000

    These guys in question are having some odd issues with their mail through their Exchange server, and I'm a bit baffled as to what's causing the problem.

    Basically there's one particular user who no one can send email to, it seems. The AD account is configured, as is the exchange mailbox. However, when someone inside the same domain tries to email her, or if I try to email her from the outside, we get a "550 User Unknown" error. That can't be right though, because I'm looking right at the mailbox in System Manager, and the corrrect email address is configured in her AD account.

    So can someone point me in a direction as to where to start looking for clues?

  2. #2
    T̙͓̞̣̯ͦͭͅͅȂͧͭͧ̏̈͏̖̖Z̿ ͆̎̄
    Join Date
    Dec 2004
    Hi AK,

    I took a look around and this is the closest I could find...but you have to register to view the answer...

    Email General: 550 5.1.1 User Unknown error (but the user is known)


  3. #3
    Senior Member
    Join Date
    Mar 2005
    Takes two to get the answer,

    This should be logged by iMail, if the server actually gets the incoming message and rejects it. Does the log say anything interesting? I think you can adjust the level of details that are logged and you may have to use the most detailed level here.

    If "Fred" cannot send mail to anyone at "John's" company, the problem is probably not with "John" but rather at "Fred's" end. Perhaps his domain has been blocked. Look in the Kill list. Also "Fred" may benefit from a look in the mail server log at his end. These error messages can be less-than-perfect when they state the problem. The returned message to "Fred" must have headers, too. Is it possible to determine if the original message ever reaches "John's" server before it bounces?
    I'm having a similar problem but think I know what the problem is.

    I think the mail is being bounced because of a reverse lookup failure
    we have a similar problem with one of our domains

    I recently started relaying our mail through an external server that we have control over
    rather than our ISP's mail systems (long story)

    Certain servers when receiving mail perform a check on the last server IP that the mail was relayed through and check to see whether it matches the reverse IP lookup on the senders domain.

    Even though I have an MX forwarder record set up to point to my relay server
    the actual domain <blahblah.com> still resolves back to my ISP's domain.

    I still have some more work to solve this issue, but i feel i'm going in the right direction

    Now you don't have to register.
    Beta tester of "0"s and "1"s"

  4. #4
    That doesn't relate so much to my issue though, because the above mentioned issue is between Fred on his mail server and John on his. In my case, these are two users on the same Exchange server. You would think that in Exchange, at least Fred@domain.com could email John@domain.com without getting a 550 user unknown error.

  5. #5
    Senior Member
    Join Date
    Mar 2005
    Sorry the cut and paste didn't work for you.

    Try this:

    Create a temporary user in Exchange for her. That's what I do, always have one temp user account to test to/from.
    Set up her workstation (Outlook or whatever you use) for that temp account.
    See if she can get email after you've sent her a piece or two.
    Then have her email someone else.

    If that works okay, then her account is corrupted.
    Beta tester of "0"s and "1"s"

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