SENT mail from one account only visible in SENT in another account

My company has a Microsoft Office 365 mail solution.
We all have personal mail account like JOE@COMPANY.DK.
All users are running Outlook 2013 / 2016.
We have an account called SALE@COMPANY.DK.

All users has configured SALE as a second Exchange account.

The problem is, that SOME of the users - not all, places SENT + DELETED mail items from SALE in their own, personal mail folders???
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Vasil Michev (MVP)Commented:
There is a registry-based workaround that controls this behavior for Shared mailboxes in Outlook. Take a loot at these articles:

Deleted items:
Sent Items:
Sunil ChauhanExpertise in Exchange Server, Office 365 & Powershell ScriptingCommented:
Sent items behavior can be controlled from the exchange side itself.

below cmds can be used to control the sent items save locations to shared mailbox itself.

For emails Sent As the shared mailbox:
set-mailbox <mailbox name> -MessageCopyForSentAsEnabled $True

For emails Sent On Behalf of the shared mailbox:
set-mailbox <mailbox name> -MessageCopyForSendOnBehalfEnabled $True

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OhmitAuthor Commented:
is this possible from Office365?? :-)
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Sunil ChauhanExpertise in Exchange Server, Office 365 & Powershell ScriptingCommented:
OhmitAuthor Commented:
Sunil Chauhan - Great thanks, going to check it out

Vasil Michev (MVP) - This is only valid for older versions of Office, Apparently not for Outlook 2016
Vasil Michev (MVP)Commented:
If you say so :)
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