Why I received Blank NDR?

Question

Hi

in our exchange 2016 environment, I have sent an email to around 16 internally and externally recipients with an attachment size of 3 MB. However, I received an NDR but it was blank or empty. there is no actual explaination why the email failed to be delivered.

I received the following message in the NDR:

Delivery has failed to these recipients or groups:

Thats it. it even did not state which recipient or groups and why.

I checked with the exchange tracking logs and there was not record of the email.

However, when i removed the attachment , it was sent without any issue. I hade similar case where i have splitted the attachment into two different emails and it was sent too.

However, our attachmetn policy is 25 MB for outlook desktop. and I was using outlook desktop.

Is there a max limit size of attachment to a long thread of recipietents although the actuall attachment is much lower than the limit(for example here its 25 MB and my attachment is 3MB) ? Appearntly the only logical reason here is that the attachment size.

Answer 1

Hi @Athique Nihal,

Welcome to the Microsoft Forum for technical support.

Based on your description, I have a few questions for you to confirm:

1.Is your 25MB attachment size limit set correctly and comprehensively? Please refer to the following steps for specific operations:

a. Check the global settings, open the Exchange Management Shell, enter the following command to view the default value of the global attachment size limit Get-TransportConfig | Format-List MaxReceiveSize, MaxSendSize, MaxRecipientEnvelopeLimit If necessary, you can use the following command to modify the attachment size limit of the global setting ( For example, change it to 25MB) Set-TransportConfig -MaxReceiveSize 36MB -MaxSendSize 25MB.

b. Check the connector settings: Use the following command to view the settings of the connector: Get-ReceiveConnector | Format-List Name, MaxMessageSize Get-SendConnector | Format-List Name, MaxMessageSize If necessary, you can use the following command to modify the attachment size of the connector Limit Set-ReceiveConnector -MaxMessageSize 25MB Set-SendConnector -MaxMessageSize 25MB.

c. Check the ActiveSync settings: Open IIS Manager, navigate to Sites > Default Website, and select Microsoft-Server-ActiveSync. Verify that the Feature View tab at the bottom is selected and double-click Configuration Editor in the Administration section. Click the drop-down arrow in the Section field, navigate to system.webServer > Security, and select requestFiltering. In the results, expand requestLimits and you will see maxAllowedContentLength and the default value of 30000000 (bytes). To change the maxAllowedContentLength value, enter a new value in bytes and click Apply.

d. Check recipient restrictions. Open EAC->Recipients > Mailboxes > Message size restriction

2.Did not everyone receive the email, or did some users not receive the email? Is there a difference between internal users and external users?

3.What is the format of the attachment? It is recommended that you try attachments in other formats and see if you can send them normally?

Please feel free to contact me if you have any queries.

Best,

Jake Zhang

Answer 2

What anti virus are you using?

If you send the over size messages with a different message format does the behavior change?

Same issue if you send from Outlook Web App?