Reason for Non-Delivery not displayed in Outlook


  • In our environment we use Sonicwall EmailSecurity appliances for our email perimeter. I noticed that when an email is bounced for something like invalid address I receive the email from the postmaster stating the the email was undeliverable but, I don't see WHY it was not delivered. I forwarded the NDR to an external account and opened the NDR I can see that there is an attachment and when I open the attachment there is the reason for the NDR. Such as below. Why don't I see this in Outlook. Is there a configuration issue in my Exchange 2013 mailbox servers? Any assistance is appreciated.

    Reporting-MTA: dns;

    Final-recipient: RFC822;
    Action: failed
    Status: 5.0.0
    Remote-MTA: dns; (
    X-Supplementary-Info: < ( #5.0.0 smtp;550
     Invalid Recipient ->

    Wednesday, December 6, 2017 4:51 PM

All replies

  • Hi,

    Based on your description, I know that you cannot see the undeliverable reasons for the NDR message.

    To confirm with you:

    1. Is there anyone else having the issue?
    2. Can you see the attachment in OWA?
    3. What is the attachment format?

    For troubleshooting:

    1. Please check if there are transport rules or other from the organization side to block the attachment.
    2. Outlook may block some specific file types, please check in this document "Blocked attachments in Outlook".

    Hope it hepls.


    Manu Meng

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    Thursday, December 7, 2017 7:59 AM
  • To answer your questions:

    Yes, everyone is having the problem. No, I cannot see the attachment in OWA. The attachment format doesn't seem to have a file association. When I open or try to save windows asks what application would I like to use.

    Thursday, December 7, 2017 8:24 AM
  • outlook express was able to open .eml messages previously. not sure if it can still open it.

    try to use it

    Thanks & Regards Ramandeep Singh

    Thursday, December 7, 2017 8:32 AM