Intermediate SMTP failure

Posted on 2006-05-23
Last Modified: 2013-12-18
I am working for a client who has a Domino server and in its log file is receiving error messages of not being able to connect to a MX server, but a few seconds later they are able to send to another MX server from the same domain.

Error transferring to; SMTP Protocol Returned a Permanent Error 550 REQUESTED ACTION NOT TAKEN: DNS FAILURE

Transferred to

Later on in the day a message was successfully transferred to  If this company has reverse dns setup, a static ip address, and not blacklisted what could be the reasoning for this kind of message?
Question by:jahhan
    LVL 46

    Accepted Solution

    Problems at AOL? When I search the Internet, I find many references to AOL with this message, e.g.
    LVL 20

    Assisted Solution

    We had horrible time with AOL recently and it was because people were marking mail from us as spam. If aol receives x number of complaints within a hour or a day then they will temporarily black list you.

    They have a feature where you can get notified anytime someone blacklists your IP address. They call it the feedback loop

    I would start with this

    Author Comment

    The email is actually being submitted but the log is stating that since it cannot use one MX server it will use the other.  It is not doing this on every instance of submitted email just sporadically, but it is everyday.  could it be that AOL has a filtering feature enabled that will cause this type of error message?
    LVL 18

    Expert Comment

    I believe that AOL gets so much mail, that when one server is overloaded, and it has the higher mx record, then mail starts to go there, the server doesn't respond in time and then it falls over to the next higher mx record.   The same is true for Hotmail, yahoo mail, etc, as well as your own SMTP servers.  If you have more than one configured, then you assign each an MX record value of how you want mail delivered.. deliver to this one, and if this one is unavailable, then deliver to this one.

    I would think that you get the error message when the AOL server gets hung and before it can clear the cache.  Unless they're adding a bit of routing logic to their servers..

    When aol puts you on a spam list, the server message say just that.. you can't deliver to me because you're on my spam list, or you're denied because you're listed in this black list, or my black list.  It's very specific.

    I'm including this because although the other responses are correct, the error message you're getting is inconsistent with those responses and the one you accepted as the correct response. Your error message is more consistent with the server being overloaded and your mail was redirected to the secondary server.

    Jahhan, your last post is the correct answer to your question.  You can ask Customer service to PAQ and refund, since you provided your own answer. :)


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