Mail Delayed

Posted on 2011-04-28
Last Modified: 2012-05-11
I have a user who occassionally gets a Mail Delayed Notification

Delivery to the following recipients has been delayed.

This mail was sent a day ago.  The user resent the mail and that message was successfully transferred to the recipient.  However, the original mail is still sitting in our queue in a retry state.

I ran SMTPDiag <sender e-mail> <recipient e-mail>

All tests passed.

I have attempted to review the SMTP log by importing into Excel.  I located the block of cells /rows for the problematic e-mail.  Problem is I don't really know what to look for in these logs.  Nothing stands out, there is nothing saying ERROR or common sense wise indicating a failure.

Why would the original message still be sitting in queue, and the second message sent to the same e-mail address make it to the desired recipient?

Based on my research from google and EE I can't seem to find a definitive cause for this notification.  If it is helpful I can post the excerpt from the SMTP log files, I just need to scrub the identifying information first.
Question by:Zorniac
    LVL 7

    Expert Comment

    The mail could have been delayed by grey listing.  The next message would be delivered successfully as the grey listing period has not expired.  The original message will wait for the retry period to expire before trying again at which point I would expect it to succeed.  Could also be that connection time spam filtering on the remote host caused a spammy looking message to be deferred.  Subsequent messages may have been less spammy in appearance.

    Is this continuing to happen or was it just a one off??  If it is happening a lot with a single remote domain then you may find that a quick email to postmaster@... will yield some answers or get you added to a white list at their end.

    Hope this helps

    LVL 1

    Author Comment

    It would seem that this is a sporadic issue and the majority of his messages succeed.  The message that made it through was identical to the first.  

    This user reports this happening to various domains he sends to, but not on a consistent basis.  This message has been retried several times since the successful delivery of the second message.  last attempt was at 11:11 (EST) next attempt is in 4 minutes 11:41.

    Based on the fact that this is a sporadic issue, do you still think it warrants an e-mail to the postmaster at this domain?  I just don't want to make a mountain out of mole hill, but at the same time I need to satisfy this users issue.

    LVL 7

    Accepted Solution

    If it happens with various domains it would point more towards a problem at your end.  Have a look at your public facing DNS servers - are they all in sync??  Does your mail servers IP address appear on any black lists??  Does your ISP have an upstream smarthost that you can relay messages through for a while??

    LVL 1

    Author Comment

    My public facing DNS servers?  We don't host any public facing DNS servers.  Have two internal DNS servers with fowarders.  Those two appear to have communication and identical records.  I did a blacklist check and we don't appear listed on any of them.  We have Verizon as an ISP and I do believe they have a smarthost available.  Additionally, we have a subscription with Trend HES, that allows us to send through them as well, but it is not configured.

    If I use VZ as smarthost, I would need to add them to my SPF record for recipient servers doing an SPF lookup correct?  What about recipient servers that do a RDNS lookup, would using the smart host cause an issue there?
    LVL 1

    Author Closing Comment

    configured Exchange to use a upstream smarthost

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