Outlook for Mac 2026 (draft)

Hi @James Ennis, 

I hope you're doing well today. 

Based on the information you shared that Outlook for Mac 16.106 on macOS Tahoe 26.3 where emails that have already been sent via IMAP later show up again in the Drafts folder.  

This typically occurs when the IMAP “special folder” mapping on the account does not fully match what the mail server expects, so Outlook may re-sync a server copy and associate it with Drafts instead of Sent. In addition, certain providers apply server-side folder rules or special-use flags that can cause Outlook to re-categorize items during synchronization.  

1/ Correct the Drafts and Sent folder mapping for your IMAP account 

• Open Outlook and select Outlook on the menu bar, then choose Settings.  
• Open Accounts, select your IMAP account, then open Advanced. Advanced IMAP account settings for Outlook for Mac - Microsoft Support 
• Go to the Folders section and ensure the following are set to the correct server folders: 
  • Store sent messages in this folder: select the server folder your provider uses for Sent (commonly Sent, Sent Items, or a provider-specific Sent folder). 
  • Store draft messages in this folder: select the server Drafts folder. IMAP account folder settings - Microsoft Support 
• Save changes, fully quit Outlook, then reopen it and send a test email to yourself to confirm it stays in Sent and does not reappear in Drafts. 

2/ Update outlook to the latest available build 

• Open Outlook and click Help in the top menu bar. 
• Select Check for Updates and allow Microsoft AutoUpdate to download and install any available patches. 
• Once complete, restart Outlook and send a test email to yourself to confirm whether the draft behavior continues. 
• Microsoft has addressed IMAP send-pipeline handling in builds released after 16.106, and this step alone may fully clear the issue. 
• Reference: Update Office for Mac automatically - Microsoft Support 

3/ Validate the server-side behavior (rules and folder flags) 

• Sign in to your mailbox using your provider’s webmail (or another email app) and compare Sent and Drafts for any duplicated copies of the same message. 
• Review any server-side Filters or Rules that might copy, move, or label outbound messages, because those actions can trigger re-sync behavior in IMAP clients. 
• If you find the same message in both folders on the server, adjust the rule so only one authoritative copy remains in Sent, then test again from Outlook. 

4/ Reset the local Outlook profile database (without removing your account) 

• Quit Outlook completely using Command + Q. 
• Open Finder, click the Go menu in the top bar, then select Go to Folder. 
• Paste the following path and press Enter: ~/Library/Group Containers/UBF8T346G9.Office/Outlook 
• Open the folder named Outlook 15 Profiles, then delete the Main Profile folder inside it. 
• Relaunch Outlook, the application will rebuild its local database and prompt you to re-add your account. Your emails remain safely on the server and will re-sync automatically. 

This step clears any corrupted local cache that may be causing Outlook to persistently recreate stale draft entries. Clear the cache in Outlook for Mac - Microsoft Support 

5/ Refresh Outlook’s local sync state without re-adding the account 

• In Outlook, use Help options that relate to resetting or clearing local application data (available depending on build), then restart Outlook and allow a full mailbox sync to complete.  
• Keep Outlook open until synchronization finishes, since an interrupted sync can reintroduce incorrect folder states during the next session.  
• If the behavior returns after a few days, create a new Outlook profile (this is different from removing and adding the account again) so Outlook builds a fresh local sync index against the same server folders. 

About switching back to Legacy Outlook 

If the option is available in your build, you can switch back by opening Outlook and selecting Help, then Revert to Legacy Outlook. Outlook for Mac - Microsoft Support  Separately, Microsoft has published timelines indicating that Legacy Outlook for Mac has support limitations moving forward, including impacts for Exchange Online in the future. 

6/ Contact in-app support  

• In New Outlook for Mac, go to Help > Contact Support.  
• This team has access to specialized diagnostic tools and deeper product insights, which can help investigate Outlook-specific behavior and provide more targeted guidance.  

As community moderators, we appreciate your understanding that our access to internal development details is limited. Our primary role is to guide users toward the appropriate resources and support channels. While we may not have visibility into deeper backend analysis, we’ll continue doing our best to support you within the scope of our responsibilities.         

I hope this information is helpful. Please follow these steps and let me know if it works for you. If you have any updates regarding the issue, please feel free to share them with me.           

Thank you for your patience and your understanding. I look forward to continuing the conversation.  

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