Hi @George Holland,
Thank you for posting your question in the Microsoft Q&A forum.
I completely understand how worrying it can be when a folder you created in the new Outlook seems to disappear after switching back to Classic Outlook. This usually happens because new Outlook and classic Outlook don’t always store or sync data in exactly the same way. Although folders created in new Outlook should appear everywhere: Classic Outlook, Outlook on the web, and mobile, differences in profiles or sync status can make it look like the folder has vanished, even when it’s still on the server. For reference, Microsoft’s feature comparison explains these differences in more detail: Feature comparison between new Outlook and classic Outlook.
In most cases like yours, the issue usually comes down to one of the following:
- Profile or account mismatch: Classic Outlook may be opening a different profile than the one used in new Outlook. As a result, the folder simply isn’t in that profile. Using the “Show Profiles” picker helps confirm you’re opening the correct mailbox.
- Folder Pane visibility issues: Sometimes the folder is there but hidden because the Folder Pane is minimized or set to a reduced view.
- Sync or offline cache problems: Classic Outlook relies on an OST file, and if the cache hasn’t synced or is corrupted, new folders don’t appear until the cache is rebuilt.
- Actual deletion: If the folder was removed, you can typically restore it using Deleted Items > Recover items deleted from this folder.
With that in mind, here are a few steps you can try right away to narrow things down:
1/ Confirm the folder exists on the server:
Start by signing in to Outlook on the web and checking whether the folder appears there.
- If the folder is visible: This confirms that the data is safe, and Classic Outlook likely needs to sync or point to the correct profile.
- If the folder is missing: Check Deleted Items > Recover items deleted from this folder to restore it. Reference: Recover and restore deleted items in Outlook.
- Reference: Recover and restore deleted items in Outlook.
2/ Make sure Classic Outlook is using the same profile:
Since profile mismatch is common, verify Classic Outlook is opening the same profile used in new Outlook.
- Go to File > Account Settings > Change Profile (Outlook will restart and show the Choose Profile dialog), or open Control Panel > Mail > Show Profiles. You may want to select Prompt for a profile if you have multiple. You can see: Switch to another Outlook email profile.
- If Classic Outlook connects but the folder still doesn’t appear, repair the profile via: File > Account Settings > Account Settings > select account > Repair, then restart Outlook. Reference: Fix your Outlook email connection by repairing your profile.
3/ Ensure the Folder Pane isn’t hiding the folder:
Depending on how the view is configured, your folder might be collapsed or hidden.
- In Classic Outlook: View > Folder Pane > Normal.
- In New Outlook: View > Folder pane > Folder list > Show.
- Reference: Show all folders in Outlook.
4/ Rebuild the offline cache (OST):
If the folder exists on the server but Classic Outlook still doesn’t show it, the OST cache may need refreshing.
- Close Outlook.
- Locate the account’s .ost file.
- Delete or rename it.
Outlook will recreate a clean copy from the server when it restarts.
Reference: Repair Outlook Data Files (.pst and .ost).
5/ Use Microsoft’s automated troubleshooters:
I hope these steps help you move forward. When you have a chance, please let me know what you find after checking Outlook on the web and verifying the profile in Classic Outlook. Your results will help narrow down the cause and guide the next steps more accurately.
Thank you again for your patience and cooperation. If you have any questions or need further assistance, don't hesitate to reach out again. I'm here to help.
I'm looking forward to hearing from you.
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