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Mail flow problem (stucked queue on exchange2013 edge with 451 4.4.0 dns query failed serverfailure)

    Question

  • Hi guys.

    Frontend - Exchange 2013 CU10

    ExchangeEDGE 2013 - CU11

    We see messages in queue on Exchange 2013 edge server with 451 4.4.0 error and can not figure it out why they dont go thru

    We have tried solving it going on Exchange 2013 FRONTEND under send connectors.
    We have choosen there send connector EDGESYNC - from SITE to INTERNET and marking: Use the External DNS lookup settings on the transport server.
    And restarting transport service on Exchange2013, but the problem remains the same.
    Please help


    bostjanc

    Thursday, January 14, 2016 1:00 PM

Answers

  • Thank you for all your help.

    Output of corp.picassotravel.com is:

    Is it ok?


    bostjanc

    That's not an MX record.  Look at the Type field, its a SOA (Start of Authority) Record.  Exchange can't route the mail without a valid mx record.

    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread

    Friday, January 15, 2016 4:14 PM

All replies

  • Check event viewer from MSExchangeTransport.

    Thursday, January 14, 2016 1:54 PM
  • From your Edge server try:

    Resolve-DnsName <domain that is failing> -Type mx

    you can also specify a server:

    Resolve-DnsName <domain that is failing> -Type mx -Server 4.2.2.2


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread

    Thursday, January 14, 2016 2:25 PM
  • Thank you for the replies:

    OUTPUT OF COMMAND: Resolve-DnsName <domain that is failing> -Type mx -Server 4.2.2.2

    Is it ok?


    bostjanc

    Thursday, January 14, 2016 5:54 PM
  • Sartaychi, I was checking event viewer, but here are no relevant WARNING/CRITICAL information (see the Picture belllow).


    bostjanc

    Thursday, January 14, 2016 6:02 PM
  • Thank you for the replies:

    OUTPUT OF COMMAND: Resolve-DnsName <domain that is failing> -Type mx -Server 4.2.2.2

    Is it ok?


    bostjanc

    Try corp.picassotravel.com since that is the next hop domain. if there is no MX record or you cant telnet to port 25 from the edge server, then someone probably got the destination email address wrong.

    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread

    Thursday, January 14, 2016 6:07 PM
  • Thank you for all your help.

    Output of corp.picassotravel.com is:

    Is it ok?


    bostjanc

    Thursday, January 14, 2016 6:09 PM
  • If I double click on EXCHANGE2013EDGE server on corp.picassotravel.com on queue window I see message with error: SMTP default internal recieve  connector...

    Am I lookin on the wrong side for the root of problem?


    bostjanc

    Thursday, January 14, 2016 6:17 PM
  • Exchange writes most events to Application. Check this.
    Thursday, January 14, 2016 8:28 PM
  • First of all i don't see "PBXCC" as a valid domain name. Make sure sender has sent the email to correct email address. If the recipient address is correct then check for the following:

    Check connectivity/send connector's log to see what's happening when its trying to send outbound emails.

    Look for the MX record of destination domain by using nslookup and then do telnet to the destination MX on port 25 to see if you can submit an email message manually.

    Please mark as Answer if this answers your question.

    • Edited by -Farrukh Friday, January 15, 2016 1:39 AM
    Friday, January 15, 2016 1:33 AM
  • Hi,

    According to your description, I understand that message queued in Edge server with error "451 4.4.0 DNS query failed".
    If I misunderstand your concern, please do not hesitate to let me know.

    Please confirm whether internal and inbound mail flow works or not.

    Please use Telnet to send message from internal to external to test SMTP communication, also here's an article about 451 4.4.0 DNS query failed Exchange Server error in message queue: https://support.microsoft.com/en-us/kb/3038746

    Once modify the connector setting, please run Start-EdgeSynchronization to force EdgeSync sync.


    Please remember to mark the replies as answers if they help, and unmark the answers if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Allen Wang
    TechNet Community Support

    Friday, January 15, 2016 5:54 AM
    Moderator
  • Thank you for all your help.

    Output of corp.picassotravel.com is:

    Is it ok?


    bostjanc

    That's not an MX record.  Look at the Type field, its a SOA (Start of Authority) Record.  Exchange can't route the mail without a valid mx record.

    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread

    Friday, January 15, 2016 4:14 PM