Why did I receive a Non Delivery Receipt(NDR)?


Why did the HENNGE Email DLP service send me a Non-Delivery Receipt?
The HENNGE Email DLP service parses the whole email, including attachments, per recipient before filtering it.
If the parsing process is not completed properly, the email cannot be delivered to the recipient(s) and the Non-Delivery Receipt(NDR) will be delivered to the sender.

- NDR Sender

From: HENNGE One Mail Delivery System <MAILER-DAEMON@bounce.mo.hdems.com>

 The address was changed from "MAILER-DAEMON@bounce.mo.hdems.com" on, January 31, 2024.

- NDR Example

This is HENNGE One mail system.
I'm sorry to inform you that your message could not be delivered to a recipient. It's attached below.
For further assistance, please contact our support.
If you do so, please include this problem report. You can delete your own text from the attached return message.
                    The mail system
<Undeliverable Recipient address>: <Error Reason(*)>

(*) Please refer to the following error reasons for details.

 Error Message  Details
 maximum uncompressed data size exceeded If the attachments are compressed, the decompressed files may be too large. Please use a file transfer service, such as HENNGE Secure Transfer,  or manually compress the files into a password-protected file before sending the email again.
Depending on the Email DLP policy set for your organization, password-protected files or compressed files may be restricted. To find out more about your organization policy, please contact your system administrator.
 Bad recipient address syntax One or more recipient email addresses are invalid. Check the addresses and send the email again.
 System error If one or more files are attached, please use a file transfer service such as HENNGE Secure Transfer, or manually compress the files into a password-protected file. Please contact your system administrator if the issue is not resolved with this method.
For system administrators, please send a message source of the sender(eml file) to Customer Success Guide for further investigation.
Reference:How to obtain a message source?
secure_transfer: too many attachments The maximum number of files that can be attached in HENNGE Secure Download is 20. Please reduce the number of attachments to 20 or less and resend the email.
secure_transfer: invalid recipient address Recipient email address is invalid. Check the recipient email address and send the email again.
secure_transfer: transfer disabled Before delivering the email, the sender disables the download link. Please check the attachments and send the email again.
secure_transfer: sender's account information is invalid Sender's account information is invalid. Please recreate that account in HENNGE Email DLP and send the email again.
secure_transfer: the integration has been disabled HENNGE Secure Download function is enabled in a rule in HENNGE Email DLP where HENNGE Secure Download service is not contracted.
Please disable HENNGE Secure Download function.

Please contact the Customer Success Guide if none of the above applies.
Please also refer to the article "What are the types of typical error emails?" about Non-Delivery Receipt from other service providers.

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