Outlook Shared Mailbox: Keep Sent and Deleted Items Where They Belong

by | Oct 10, 2026 | email, Microsoft Office

If you work in more than one mailbox in Outlook, such as your own plus a shared info@, office@, or billing@ mailbox, you may have run into a frustrating problem. You send a reply from the shared mailbox, and the copy shows up in your Sent Items instead of the shared mailbox’s. You delete a message from the shared mailbox, and it lands in your Deleted Items.

The result is that your coworkers can’t see what was already answered, and messages appear to vanish from the shared mailbox. The good news is that the fix is quick.

Why This Happens

By default, classic Outlook treats your own mailbox as “home base.” When a shared mailbox is added to your Outlook automatically (which Microsoft 365 does when you’re given access), Outlook files sent and deleted items from it in your personal folders. That made sense years ago, when shared mailboxes were rare. For today’s small offices, churches, and nonprofits, where several people answer the same mailbox, it causes confusion.

The Fix

Two Windows settings tell Outlook to keep sent and deleted messages with the mailbox they came from. To apply them, close Outlook, open a Command Prompt (not as administrator; these settings belong to your user account), and run these two commands:

reg add "HKCU\Software\Microsoft\Office\16.0\Outlook\Preferences" /v DelegateSentItemsStyle /t REG_DWORD /d 1 /f
reg add "HKCU\Software\Microsoft\Office\16.0\Outlook\Preferences" /v DelegateWastebasketStyle /t REG_DWORD /d 4 /f

Then reopen Outlook. From now on:

  • Messages you send from the shared mailbox are saved in the shared mailbox’s Sent Items.
  • Messages you delete from the shared mailbox go to the shared mailbox’s Deleted Items, where your coworkers can still find them.

These settings apply to Outlook 2016, 2019, 2021, 2024, and Microsoft 365. Each person who uses the shared mailbox needs them on each computer they use.

A Note for Microsoft 365 Administrators

For Exchange Online, Microsoft offers a server-side setting that saves sent items to the shared mailbox no matter which device or app was used, including Outlook on the web, phones, and the new Outlook:

Set-Mailbox [email protected] -MessageCopyForSentAsEnabled $true -MessageCopyForSendOnBehalfEnabled $true

Use either this server-side setting or the DelegateSentItemsStyle registry value for sent items, not both, or you may end up with two copies of every message. There is no server-side equivalent for deleted items, so the DelegateWastebasketStyle setting is still worth applying.

When This Doesn’t Apply

If each mailbox was added to Outlook as its own separate account (File › Add Account), Outlook already keeps sent and deleted items separate, and these settings won’t change anything. The same is true for IMAP and POP accounts from providers like Gmail or your web host, which are set up through each account’s own settings.

Want Us to Handle It?

Katy Computer Systems clients don’t need to touch the registry. Just open a ticket or give us a call, and we’ll apply the fix across every workstation in your office, so your shared mailboxes work the way your team expects.