We can close this as unresolved. We will manage the issue until we switch to Exchange online.
Hi
@TRDx2
,
Have you set any transport rules to check the emails?
And what;s the version of your Exchange server?
If you're using O365, please see this article:
https://learn.microsoft.com/en-us/exchange/troubleshoot/email-delivery/invalid-message-ndr
This issue may occur if the following conditions are true:
A transport rule is set up that has the Defer the message if rule processing doesn't complete option enabled.
During text extraction, the scanning process timed out when inspecting the attachment.
If that's not the case, then I think something is trying to or having changed the type of your email format.
You don't have to disable AV, check if there are some options that do effect the email context.
Best regards,
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Hi Lou,
Thanks for responding. To answer your questions, We are using a 4 node DAG running Exchange 2016.
None of our transport rules have defer the message if rule processing doesn't complete enabled.
This issue is intermittent and I am not sure what would be changing the email format. I think I will start by getting with our anti-virus vendor and see if they have something that would be causing this. If I can't find anything there. I will see about disabling add-ins for Outlook. Not sure where to go after that.
I am open if anyone has any guidance on what to check.
Thanks,
Hi
@TRDx2
,
How about everything going?
Have you tried using outlook/safe to diable add-ins?
And are there rules about checking the attachments?
Best regards,
The issue with testing is that it happens randomly. It may be several days before anyone in the company may get the error. Getting all users to make sure they open Outlook in safemode is not possible. Disabling add-ins is problematic as if the error doesn't happen with in a few hours the users start calling to get their add-ins enabled again.
We don't do any attachment scanning from clients or Exchange. Asking all our users to stop using Outlook and start using OWA is not possible.