Help Re: Exchange: Error 550 User Unknown After Restart

Posted on 2009-02-23
Last Modified: 2013-11-30

I restarted an SBS2003 server this morning after some updates and now when anyone from outside tries to send to any internal user they get their email bounced back with the message below:

   SMTP error from remote mail server after RCPT TO:<>:
   host [194.x.x.x]: 550 User unknown

Exchange was working fine before this. We can email out OK and OWA still works, just not accepting incoming messages.

Question by:mr-gadget
    LVL 21

    Expert Comment

    did you apply the latest exchange updates also?
    did you rerun the connect to the internet wizard (which configures all exchange settings for you)?
    and events in the eventlogs related to the problem?
    LVL 21

    Accepted Solution

    so for the CEICW, let it run again, escpecially the email part:
    a. Open Server Management.
    b. Click To Do List.
    c. Click Connect to the Internet.
    d. Proceed to the "Firewall" page and select "Enable Firewall".
    e. On the "Services Configuration" page, make sure that "E-mail" service
    has been checked.
    f. On the "Web Services Configuration" page, check the web services that
    you want to publish.
    g. On the "Web Server Certificate" page, choose "Create a new Web server
    certificate" and key in your public domain name in the box.
    h. On the "Internet E-mail" page, choose "Enable Internet e-mail".
    i. On the "E-mail Delivery Method" page, choose DNS (Use DNS to route
    e-mail) or Smart Host (Forward all e-mail to e-mail server at your ISP) to
    route your email, If you select smart host, you need to input the IP
    address of your smart host.
    j. If you're using POP3 connector, please enable POP3 Connector.
    k. Key in your e-mail domain name in "Email Domain Name" page. (Input here)
    l. Finish the wizard.

    I guess you didn't change your mx settings?
    LVL 5

    Author Closing Comment

    I didn't use your solution in the end as I resolved it myself, however it looks comprehensive and I'm sure I will find it useful anyway.

    It now looks like the problem wasn't much of a problem after all but was more of a ball of confusion  caused by three factors:

    1. Server taking WAY WAY longer to start all services than I would have expected, so several 'GOOD' or previously working mailboxes didn't come online straight away.
    2. Weird MX / A name combinations at the domain host that I wasn't expecting. I.E. The previous support company had set mail forwarding per user rather than the whole domain to the server,
    3. A certain amount of 'blondeness' on my part.

    I think it all finally came back to life after I did a full shutdown, as opposed to restart and after I contacted the domain host and they informed me that they were not routing all email to the server. Doh!

    Thanks for your help anyway. :-)

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