This the scenario
User A sent an email to User B. User B replied to the email and User A did not receive it and User A raised a Ticket that even though User B replied User A did not receive the email. So I did a mail trace and the event id Deliver showed under the recipients User A. I checked the user outlook client and performed advanced search using search tools and it did not show up.
I also ran the command search-mailbox on the User A mailbox with the subject and also did not find it. User B outlook client is running in online mode.
Not sure even though the event id Deliver trigger I am not able to see the User B reply to User A,
Exchange server : CU 13
outlook client 2016