Today I came across a new issue in outlook which I want to share with you guys. One user in my organization reported that when he is trying to send an email to a shared mailbox he is getting an undelivered NDR message as mentioned at the bottom: (Email Getting Forwarded-NDR message-X-MS-Exchange-Inbox-Rules-Loop)
After Analyzing this NDR message, I found that user Estell.Bea@*****.gov of our organization who is a member of the shared Mailbox has forwarded his emails to his personal Gmail account *********@gmail.com due to which when an email is being sent to shared mailbox users were getting NDR message for this Gmail account.
Resolution:- I have resolved this issue by removing forwarding Email through below PowerShell command and informed the user not to set up any forwarded email which is outside the organization.
Powershell command to know if any rule is set up on a mailbox:-
Get-Mailbox -Identity "priya.kath@******.gov" | Select-object ForwardingSmtpAddress
Powershell command to remove the Forwarding rule from the mailbox:-
set-Mailbox -Identity "priya.kath@*****gov" -ForwardingSmtpAddress $null
You can verify this by going to web outlook of the mailbox from which you have removed the forwarding mailbox or via PowerShell command:-
In Outlook Web App, select Settings Settings icon > Options > Account > Forwarding (or Mail > Accounts > Forwarding).
Get-Mailbox -Identity "priya.kath@*****.gov" | Select-object ForwardingSmtpAddress
Above command shows 0 results which means that the rule has been removed.
NDR Message for your reference
Delivery has failed to these recipients or groups:
Your message couldn't be delivered. Despite repeated attempts to contact the recipient's email system, it didn't respond.
Contact the recipient by some other means (by phone, for example) and ask them to tell their email admin that it appears that their email system isn't accepting connection requests from your email system. Give them the error details shown below. It's likely that the recipient's email admin is the only one who can fix this problem.
For more information and tips to fix this issue see this article:
Diagnostic information for administrators:
Generating server: CY1PR09MB0.namprd9.prod.outlook.com
Receiving server: CY1PR09MB0.namprd9.prod.outlook.com
Total retry attempts: 193
6/23/2016 7:01:15 PM - Server at CY1PR09MB.namprd9.prod.outlook.com returned '550 5.4.300 Message expired'.