Outlook Error 0x8004060C: Stuck Outbox Message Recovery Steps

Outlook error 0x8004060C appears when a message in the Outbox cannot be sent and blocks the outbound mail queue. This error is caused by a corrupted outgoing message, often due to a large attachment, a damaged email draft, or a conflict with an add-in. This article explains why the error occurs and provides step-by-step recovery steps to clear the stuck message and restore normal sending.

You will learn how to identify the problematic message, move or delete it, and rebuild the send/receive environment. The instructions cover Outlook 2016, Outlook 2019, Outlook 2021, and Outlook for Microsoft 365 on Windows 10 and Windows 11.

No data loss occurs if you follow the steps in order. The stuck message can be recovered and resent after the fix is applied.

Why Outlook Shows Error 0x8004060C

Error 0x8004060C is a Messaging API error that indicates a corrupted item in the Outbox. The corruption usually comes from one of these sources:

• A very large attachment that exceeds the mail server limit
• A damaged email draft that was saved and then moved to Outbox
• A conflict with an Outlook add-in that modifies outgoing messages
• A synchronization error between Outlook and the mail server

When Outlook attempts to send the corrupted message, the MAPI call fails and returns error 0x8004060C. Outlook then stops processing the Outbox queue, so all subsequent messages also remain unsent. The error repeats each time Outlook tries to send, creating a loop.

The fix requires removing the corrupted message from the Outbox. Once the message is moved or deleted, Outlook resumes normal sending for all other queued items.

Steps to Clear the Stuck Outbox Message

Perform these steps in order. Do not skip step 1 — working offline prevents Outlook from repeatedly failing and generating more errors.

1. Switch Outlook to Offline Mode
   Open Outlook. Go to the Send/Receive tab. Click the Work Offline button. The button will highlight to indicate that Outlook is now offline. This stops all send/receive operations so you can safely access the Outbox.
2. Open the Outbox Folder
   In the folder pane on the left, expand your mailbox. Click the Outbox folder. If you do not see the Outbox, click the ellipsis (three dots) at the bottom of the folder list and choose Folders, then select Outbox.
3. Identify the Stuck Message
   Look for the message that has a sending icon (a small envelope with a clock) or a red X. This message is the one causing error 0x8004060C. If multiple messages are stuck, start with the oldest one.
4. Move the Stuck Message to Drafts
   Click and hold the stuck message. Drag it to the Drafts folder in the folder pane. Release the mouse button. The message moves out of the Outbox and becomes a draft that you can edit or delete.
5. Delete the Corrupted Message (if editing fails)
   If the message cannot be moved or if it still shows errors when opened, right-click the message in the Outbox and choose Delete. Confirm the deletion. The message is removed permanently.
6. Disable Automatic Sending Temporarily
   Go to File > Options > Mail. Under the Send/Receive section, uncheck Send immediately when connected. Click OK. This prevents Outlook from immediately trying to send the message again after you go back online.
7. Go Back Online and Send
   Return to the Send/Receive tab and click Work Offline again to go back online. Press F9 to manually trigger a send/receive. Outlook should now send all other messages in the Outbox without error 0x8004060C.

If the Outbox Is Empty but the Error Persists

Sometimes the corrupted message is hidden. Close Outlook. Open File Explorer and navigate to:

C:\Users\[YourUsername]\AppData\Local\Microsoft\Outlook\

Rename the file Outlook.srs to Outlook.srs.old. Restart Outlook. This file stores the send/receive settings. Outlook creates a new one automatically.

If Outlook Still Has Issues After the Main Fix

Outbox Message Reappears After Deletion

If the same message reappears in the Outbox after you delete it, the message is stored on the mail server. Open Outlook in safe mode by holding the Ctrl key and clicking the Outlook icon. In safe mode, delete the message again. This bypasses add-ins that may be regenerating the item.

Error 0x8004060C Returns When Sending a New Message

This indicates that the corruption is in the Outbox folder itself, not in a single message. Run the Inbox Repair Tool (Scanpst.exe) on your Outlook data file. Close Outlook. Go to C:\Program Files (x86)\Microsoft Office\root\Office16 or the equivalent path for your version. Run SCANPST.EXE. Browse to your PST or OST file and start the scan. After repair, restart Outlook and try sending again.

Large Attachment Still Blocks Sending

If the stuck message has an attachment larger than your mail server limit, you cannot send it as-is. Open the message from the Drafts folder, remove the attachment, and send the message without it. Use a file-sharing service like OneDrive to share the large file separately.

Manual Send/Receive vs Automatic Send: Key Differences

Item	Manual Send/Receive (F9)	Automatic Send (Send immediately when connected)
Trigger	User presses F9 or clicks Send/Receive All Folders	Outlook sends as soon as the message leaves the Outbox
Error handling	Error appears once per manual attempt; user can close the dialog	Error loops continuously until the corrupt message is removed
Best use case	After clearing a stuck message to verify the fix	Normal daily use when no errors are present
Configuration location	Send/Receive tab > Send/Receive All Folders	File > Options > Mail > Send immediately when connected

You can now clear the stuck Outbox message and resume sending email in Outlook. After recovery, consider disabling automatic sending permanently if you frequently work with large attachments or unstable add-ins. To prevent future errors, keep your Outlook data file under 50 GB and run the Inbox Repair Tool quarterly if you experience repeated corruption.