In Microsoft Outlook, most actions can be performed by checking the ribbon or pressing a simple keyboard shortcut. For example, to delete a message in Outlook, select the message and press the Delete key on your keyboard. Although you are familiar with these things, it is quite possible that Outlook will still generate an error.
There may be times when a message is not deleted in Outlook. You see error messages such as:
- The operation failed. Mail interfaces returned an unknown error. If the problem persists, restart Outlook.
- The messaging interface caused an unknown error.
- An unknown error has occurred.
At first glance, it’s hard to pinpoint the reason that caused this error. With that said, here is what you can do to fix the Outlook error message:
Use keyboard shortcuts to delete
Among several keyboard shortcuts that you probably remember, this one will come in handy. Here is how it works:
Step 1: Select the message to delete.
2nd step: Hold down the Shift button on your keyboard.
Step 3: Press the Delete button on the keyboard.
Step 4: You should receive a pop-up message from Microsoft Outlook asking you to confirm the permanent deletion of the email. Click on Yes.
Clear deleted items
One of the reasons Microsoft Outlook displays an error message when trying to delete an item may be because the Deleted Items folder is full. When the Deleted Items folder is full, you cannot delete Outlook messages.
To correct this error, you must empty the Deleted Items folder. Here is how it works:
Step 1: In the Microsoft Outlook Folder Pane, right-click the folder labeled Deleted Items.
2nd step: From the list of options, select Empty Folder.
Step 3: You should receive a pop-up message from Microsoft Outlook asking you to confirm the permanent deletion of all items from the folder. Click on Yes.
Step 4: navigate to the message to delete and tap the Delete icon.
Edit mail marked for deletion
A corrupted mail file may also not be deleted. The best way to delete such a file is to edit it by following the steps below:
Step 1: Double-click on the message in question to open it.
2nd step: On the ribbon, find a field named Move and select the More Move Actions icon.
Step 3: From the drop-down menu, select Edit Message.
Step 4: Type a few characters or delete a few characters from the email.
Step 5: Save the message and close it.
Step 6: Navigate to the message to delete and tap the Delete icon.
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Mark the items to delete in the settings
This option only works with Microsoft Outlook accounts configured with IMAP. Here is how it works:
Step 1: Close Microsoft Outlook.
2nd step: Launch Control Panel on your PC.
Step 3: Click on Mail. If you don’t see the Mail option, change the View By setting to Small Icons or try using the search bar.
Step 4: In the new menu called Email Setup – Outlook, click Email Accounts.
Step 5: A new menu called Account Settings should open. Double click on your email name to reveal its properties.
Step 6: Click More Settings.
Step 7: Select the Advanced tab.
Step 8: In the menu named Deleted Items, make sure the following items are checked:
- Mark the items to delete but do not move them automatically. Under normal circumstances, when you mark items for deletion, they are permanently deleted when the mailbox is purged.
- Purge items when switching folders online.
Use the inbox repair tool
Another reason that Microsoft Outlook mail may not be deleted can be due to corruption of PST file. PST stands for Personal Storage Table and it is the file format in which emails, calendar events and other items are saved on Outlook. To repair a PST file, you will need the inbox repair tool. Here is how it works:
Step 1: Close Microsoft Outlook.
2nd step: Launch File Explorer.
Step 3: Open your C: Drive.
Step 4: Select Program Files.
Step 5: Select Microsoft Office.
Step 6: Select your version of Office (Office 14, 15, 16, etc.).
Step 7: Double click on SCANPST.EXE to run the file.
Step 8: Click Browse to select the PST file to scan.
Step 10: Click Yes when prompted to confirm the creation of the backup.
Step 11: Close the tool when the process is complete.
Step 12: Relaunch Microsoft Outlook and check if the problem is resolved.
Restart Outlook in Safe Mode
To restart Microsoft Outlook in safe mode, here’s what you need to do:
Step 1: Hold down the CTRL key.
2nd step: Click on the Outlook shortcut.
Step 3: You will see a warning dialog box asking you to confirm if you want to launch Outlook in Safe Mode. Click on Yes.
Last updated on July 3, 2021
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