Hi,

I encounter a strange behaviour on an Exchange 2010 organization.

There are 3 MBX/CAS/HUB physical servers in DAG and 1 physical load balancer for the CAS Array.

The Outlook Clients connect to the CAS Array, all are 2010.

Yesterday some users claim that they didn't receive messages from other internal colleagues. The message appear in "sent elements" but I can't find the message on the server...

Nothing in queues, nothing in Message Tracking, no error message in return... It is like the message left Outlook without even connecting to the Hub...

Have anyone encoutered this issue before ?

You think it is client related (Outlook) ? Maybe the load balancer ? What can I enable in logging for further investigations ?

Thank you for your replies.

Sorry for my english...

Is there anything in the SMTP queues?

As stated above, unfortunately there was nothing in the different queues...

Are the messages stuck in the Outbox?

You can check by setting Outlook to online mode or using OWA lite.

Not stuck, they appear in "sent items" folder.

Hi,

Firstly, please make sure the message tracking is enabled on all mailbox server.

Are there any transport rules related to this issue?

And please disable anti-virus software temporarily to check this issue.

Best Regards.