Relaying denied. Proper authentication required

Posted on 2010-01-04
Last Modified: 2012-05-08
Hello, we are using SBS 2003. Nothing has changed on our end.

When we try to email on domain in particular, which we used to be able to email without any problems at all, we are now getting Relaying denied. Proper authentication required.

I have not changed anything on our server, could it be on their end?  Any suggestions?

Thank you
Question by:cas_three
    LVL 58

    Expert Comment


    That error indicates there is some problem during the mail flow which is preventing any relaying of mail taking place. There is either a mis-configuration on the recipient's server, or an error on one of the hops between you and them.

    How do you send email out? Via direct delivery (DNS) or smart host? If the former, I would suggest it is their error. However, if the latter, you may want to check your smart host configuration has not changed, or check with the ISP if they have made any changes.


    Author Comment

    We do not use a smart host, Exchange 2003, direct delivery.

    It's only happening with one domain, very strange.  Makes me think they made a change since we have made none.
    LVL 58

    Accepted Solution


    If it's direct delivery, and only occurring for one domain, that does indicate it is an issue at their end.

    All email servers accepting email from the Internet need to accept email anonymously. For mail to be delivered to other servers, your server is clearly authenticating anonymously correctly, so it is a problem at the recipient's end.

    There's not a lot you can do until they resolve their issue.


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