How do I delete emails from the Outbox server file?

Question

Hello,

We have had issues with a client and their outbox folder in outlook for quite some time now. It seems whenever a network connectivity issue arises, messages that they send during that issue both get sent but also get saved to a "server folder" of the outbox folder.

Whenever a network connectivity issue arises, and eventually gets resolved, the outbox folder suddenly gets to synchronizing, and it downloads messages from this "server folder" from up to how ever long the user has their synchronization time set to (in this case 1 year, and earlier, lifetime). This time only messages since December 2024 got downloaded, but earlier we have had all the messages download and they go back to sometime mid-2023.

This "network connectivity issue" can be replicated by pressing the "Work offline" button under the Send/Receive tab, and then unselecting this option. It then synchronizes all the folders, including the outbox. I say this replicates the issue because this is the only consistent way I got to actually synchronize the local outbox with the "server folder".

Clicking on properties on the outbox folder and then navigating to synchronization shows that 39 messages are saved in the "server folder".

"Utkorg" is the Swedish name for "Outbox". This is a different machine and thus does not show the last synchronization date, the trouble machine does.

I have tried both deleting the email messages when they appear on the local machine, aswell as moving them to a different folder after appearing, and then deleting the entire new folder with the messages inside. None of this has any effect, whenever you go to properties > synchronization it still shows 39 messages saved in the "server folder", and they still get downloaded and show up when you synchronize using the method I described above.

I have access to the domain administrator account so there are no limitations in that regard. Where, if anywhere, can I delete these messages?

Thanks in advance!

Answer 1

Hi Love Givik , 

Welcome to Microsoft Q&A Forum! 

Have a good day and I hope you're doing well! 

Thank you for sharing the details. I completely understand how frustrating it can be when the Outbox keeps syncing and pulling old messages back from the server. This behavior usually relates to how Outlook synchronizes with the Exchange mailbox, especially after network interruptions or when using Work Offline mode. 

To find the most accurate solution, I’d like to clarify a few points: 

Confirm Your Exchange Environment 

Are you using: 

• Exchange Online (Microsoft 365) 
• On‑premises Exchange Server in your own domain 
• Hosted Exchange from another provider 

If it’s on‑prem, do you know which Exchange version (2013/2016/2019, etc.)? 

Cached Mode & Sync Details 

• On the affected workstation, is the account configured with Cached Exchange Mode enabled? 
• Have you already tried creating a new Outlook profile for this mailbox on that same machine? If yes, did the “39 messages on server” behavior persist or change? 

I hope this helps us narrow down the issue. I look forward to your response so I can gather more insights and provide the most suitable troubleshooting steps. Thank you for your cooperation. I truly appreciate your effort on this!

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