Outlook fix | Windows | classic Outlook
Shared mailbox sent items saving to your own?
If mail you send from a shared mailbox keeps landing in your own Sent Items instead of the shared mailbox's Sent Items, that's Outlook's default behaviour — annoying, but not a fault, and it means colleagues can't see what's been sent from the shared address. The proper fix is done in Microsoft 365: switch on the mailbox setting so Exchange saves a copy in the shared Sent Items for everyone. There's also a per-PC registry fix (DelegateSentItemsStyle) that does the same thing on one computer. Below is exactly how to do each — and the one important rule about not using both at once. We're happy to set it up for you remotely. Rated 4.9 on Google.
- ● Windows only
- ● Classic Outlook
- ● Best fixed in Microsoft 365
Answer first
Why sent mail lands in your own Sent Items
By default, when you send an email as or on behalf of a shared mailbox, Outlook keeps the copy in your own Sent Items — the personal one on your account — not in the shared mailbox's Sent Items. That's Microsoft's out-of-the-box behaviour. It causes real headaches for teams: your colleagues open the shared mailbox, look in its Sent Items, and can't see the reply you just sent, so someone answers the customer twice.
The good news is there's a clean, official fix that makes sent mail save into the shared mailbox's Sent Items so everyone can see it. The best place to set it is Microsoft 365, because it then works for every person who uses that mailbox, on any computer, automatically. There's also a registry option for a single PC — useful in specific cases — covered further down.
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The recommended fix
Turn it on in Microsoft 365 (works for everyone)
This is the fix we recommend, because it's applied once at the mailbox and covers the whole team. It's a quick command run by whoever administers your Microsoft 365 (using Exchange Online PowerShell):
- For mail sent as the shared mailbox:
Set-Mailbox "Shared Mailbox" -MessageCopyForSentAsEnabled $true - For mail sent on behalf of the mailbox:
Set-Mailbox "Shared Mailbox" -MessageCopyForSentOnBehalfEnabled $true
Once it's on, Exchange itself drops a copy of every outgoing message into the shared mailbox's Sent Items — no change needed on anyone's PC, and it works in classic Outlook, the new Outlook, Outlook on the web and the mobile app. It can take a short while to start applying after the command is run. If we look after your Microsoft 365, this is a two-minute job we can do for you; if another provider does, they can run the same command.
The per-PC alternative
The DelegateSentItemsStyle registry fix (one computer)
If you can't get the mailbox setting changed, classic Outlook has a per-computer workaround using a registry value called DelegateSentItemsStyle. It only affects the one Outlook profile on the one PC where you set it, so it's a fallback rather than the ideal fix:
- Close Outlook completely.
- Press Windows key + R, type
regeditand press Enter. - Go to
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences(the16.0covers Outlook 2016, 2019, 2021, 2024 and Microsoft 365). - Right-click in the empty space on the right, choose New > DWORD (32-bit) Value, and name it
DelegateSentItemsStyle. - Double-click it and set the value data to 1.
- Close the registry editor and reopen Outlook.
For this to work, that Outlook profile must be running in Cached Exchange Mode — if it's in online mode, sent mail can get stuck in the Outbox instead. Editing the registry is safe if you follow the steps exactly, but if you're unsure, let us do it.
Important
Don't use both fixes together
Here's the rule that trips people up: use the Microsoft 365 setting or the registry value, but not both. If MessageCopyForSentAsEnabled is switched on in Microsoft 365 and the DelegateSentItemsStyle registry value is set on a cached PC, they fight each other — you can end up with sent mail duplicated (two copies in the shared Sent Items), missing, or stuck in the Outbox.
So if you're moving to the recommended Microsoft 365 fix, first delete any DelegateSentItemsStyle value from the registry on every affected PC, then reopen Outlook. If you're relying on the registry fix on a single machine, make sure the mailbox setting is off. Getting this combination right across a team is exactly the kind of thing we sort out cleanly and quickly, so nobody's sent mail goes astray.
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// GOOD QUESTIONS
Frequently asked
Why does mail from a shared mailbox save to my own Sent Items?
That's Outlook's default behaviour: when you send as or on behalf of a shared mailbox, the copy stays in your personal Sent Items, not the shared mailbox's. It means colleagues can't see what's been sent from the shared address. You fix it by turning on the mailbox setting in Microsoft 365, or the DelegateSentItemsStyle registry value on the PC.
How do I make shared mailbox sent items save to the shared mailbox?
The recommended fix is in Microsoft 365: an administrator runs Set-Mailbox "Shared Mailbox" -MessageCopyForSentAsEnabled $true (and -MessageCopyForSentOnBehalfEnabled $true for on-behalf sending). Exchange then saves a copy in the shared mailbox's Sent Items for everyone, on every device, with no change needed on individual PCs.
What is the DelegateSentItemsStyle registry fix?
It's a per-computer workaround for classic Outlook. Close Outlook, run regedit, go to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences, create a DWORD value named DelegateSentItemsStyle and set it to 1, then reopen Outlook. It only affects that one Outlook profile, and the profile must be running in Cached Exchange Mode or mail can stick in the Outbox.
Which is better — the Microsoft 365 setting or the registry fix?
The Microsoft 365 setting (MessageCopyForSentAsEnabled) is better because it's applied once at the mailbox and works for everyone who uses it, on any computer and any Outlook version. The registry fix only covers one profile on one PC, so it's a fallback for when you can't change the mailbox setting.
Can I use both the Microsoft 365 setting and the registry value?
No — use one or the other, never both. If MessageCopyForSentAsEnabled is on in Microsoft 365 and DelegateSentItemsStyle is also set on a cached PC, they conflict and sent mail can be duplicated (two copies in the shared Sent Items), lost, or stuck in the Outbox. If you switch to the Microsoft 365 fix, delete DelegateSentItemsStyle from the registry on every affected PC first.
Can 365 Techies set this up for me?
Yes. We'll switch on the right Microsoft 365 setting so shared-mailbox sent mail saves where your whole team can see it, and tidy up any conflicting registry values — remotely while you watch, usually in minutes. We phone first and access ends when it's done. Call 01202 775566.
Sent mail still landing in the wrong place?
Call 365 Techies on 01202 775566. We'll switch on the right setting so shared-mailbox sent mail saves where the whole team can see it — remotely while you watch, usually in minutes. We phone first and access ends when it's done. Same-day help across Bournemouth and Dorset.
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