Lets assume I am the owner of the mailbox "george@example.com" and via the Exchange Online administration I allow the owner of "john@example.com" to send emails as "george@example.com" while I am out of office.

Will those emails be stored in the Sent Items folder of the "george@example.com" mailbox, or will they remain only in the "john@example.com" mailbox?

I am currently using Office 365 with Exchange Online and I send/receive emails via Outlook 365 and Outlook online.

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    This is a perfectly valid question for everyone managing Exchange Online (or on-premises); how could someone vote to close it as "not reasonable business IT management practices" or "belonging on SuperUser"?!? – Massimo Jan 29 '16 at 15:31

It depends on how the messages are being sent.

A shared mailbox can be configured to store a copy of messages sent in its name:



Basically, you need to use the following command on the shared mailbox:

Set-Mailbox <MailboxName> -MessageCopyForSentAsEnabled  $true

The same can also be done for whoever is sending on behalf of you, instead of as you:

Set-Mailbox <MailboxName> -MessageCopyForSendOnBehalfEnabled  $true

However, this only applies to native Exchange clients (i.e. Outlook, OWA); if the user is sending via SMTP submission, sent messages are never stored by Exchange anywhere.

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  • Thank you for the fast reply. In your answer you mention shared mailbox. Since shared mailbox is an technical term with ExchangeI would like to clairfy. I am not planning to use a "shared" mailbox I am planning to use a normal user mailbox and then give send permissions to an other mailbox. If I understand your answer even then if the delegated user sends as the original email through Outlook or Outlook Online the emails sent are going to be saved on the original mailbox's sent folder. Is that correct? Again thank you for your insight! – QuantumBITS Jan 29 '16 at 15:14
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    Yes, that setting is meant mainly for shared mailboxes, but it also applies to standard user mailboxes on which you are delegating send permissions. – Massimo Jan 29 '16 at 15:20
  • Perfect! I am going to test this out during the weekend and will let you know! one last thing. Do you know how to implement the command you mentioned via the GUI of office 365 exchange admin? – QuantumBITS Jan 29 '16 at 15:23
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    This can't be done via GUI, only via PowerShell; if you need instructions on how to use remote PowerShell to manage Exchange Online, you'll find them here: technet.microsoft.com/en-us/library/jj984289(v=exchg.160).aspx. – Massimo Jan 29 '16 at 15:26
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    @Massimo, -MessageCopyForSentAsEnabled and -MessageCopyForSendOnBehalfEnabled do in fact only work with Shared Mailboxes. They do not work with regular Mailboxes and perhaps you should edit your answer to reflect that. – Daniel Jul 27 '16 at 9:20

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