Sent items showing up in wrong mailboxes sent items

changing the registy will work only for single user, run the below comman on Exchange to set sent items for share mailbox. Restart of outlook is required after changing this setting on exchange server and give some time to replicate the changes globally.

Set-MailboxSentItemsConfiguration "SharedMailbox" -SendAsItemsCopiedTo SenderAndFrom

How do you have this shared mailbox attached to this user's Outlook profile?  

1: under Account Settings > open these addition mailboxes.

2:'account settings as a second mailbox
Set-mailboxpermission -identity mailbox -user %username% -accessrights fullaccess -inheritancetype all  -automapping $true
Or used EMC to set this permission?

If you added the user via the first option this might be the case. Try removing it from setup 1 and try setup 2. Allow for replication (5 mins or so in a small environment). Open Outlook and see if it is mounted. If so the when you send from that mailbox the sent items go into that shared mailbox sent folder.

hey Amit that registry key alteration worked a treat but on the 15.0 folder outlook.
would the same thing apply on the deleted items if you do the same but change the name of the new dword record to  DelegateDeleteItemsStyle with the value set to 1

Yeah sorry I gave you for 14.0. Great to know it was worked after changing 15.0

Please use below for deleted items:

1. HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Options\General

2. Look for the DelegateWastebasketStyle DWORD (if it doesn’t exist, create it)

3.        Change its value to

a.        8 - Stores deleted items in your folder

b.        4 - Stores deleted items in the shared mailbox folder

4.        Restart Outlook

Hi Amit, The General folder only exists in the 14.0 folder and not the 15.0 this time I created the D word you mentioned above but the deleted item still went to the personal mailbox deleted items.