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Outlook fix · classic Outlook (Windows)

Fix Outlook error 0x8004010b (sending reported error)

If Outlook shows "Sending reported error (0x8004010b)" and your email is stuck in the Outbox, it almost always means Outlook is pointed at the wrong data file, your mailbox is full, or a Google Workspace profile has become tangled. The good news: it's usually a five-minute fix. Below is the plain-English cause and the exact, safe steps to clear it — and if you'd rather not touch settings, we'll fix it remotely for you in minutes.

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By the 365 Techies team · Reviewed 6 October 2026

What it means

What error 0x8004010b actually means

Error 0x8004010b is a "data file" or "default store" problem. When you hit Send, Outlook tries to write the message into the data file it thinks is your main mailbox. If that file is missing, the wrong one is marked as default, or the mailbox behind it is full, the send fails and the message sticks in your Outbox with this code.

It shows up most often after you add a second account, move or restore a PST file, or on Google Workspace accounts that use the Google Workspace Sync tool (GWSMO), where a tangled profile is the usual trigger. None of this means your email is lost — it's a plumbing problem, not a data problem. Work through the steps below in order and stop as soon as your email sends.

// WINDOWS PCS ONLY

We do not support Outlook on Apple Macs, iPads or iPhones. Apple does not allow our remote-support tool to take control of an iPad or iPhone (an Apple restriction), and our remote support covers Windows PCs only. On an Apple device, Microsoft’s own Outlook help is the place to start.

// FIX IT WITH ME · STEP BY STEP

Fix it with me, one step at a time

The steps from this guide, one at a time, in the order that fixes the most cases fastest. Tell it what happened and it shows the next step. Nothing here leaves your device.Last reviewed 6 October 2026

Checking which Windows you have…STEP 1 OF 4
  1. 01Check the mailbox isn't full

    Empty Deleted Items, clear large Sent items, and for Google Workspace check your Google storage isn't full. Then try sending again.

    Is it working now?

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The fix

How to fix 0x8004010b in classic Outlook

These steps are for classic Outlook for Windows. Do them in order and stop as soon as your email sends.

  1. Check the mailbox isn't full. If you're near your storage limit, sends can fail. Empty Deleted Items, clear large messages from Sent Items, and (for Google Workspace) check your Google storage isn't full at the same time. Then try sending again.
  2. Set the correct data file as default. Go to File > Info > Account Settings > Account Settings, then open the Data Files tab. Click the data file that belongs to the account you're sending from, then click Set as Default. Click Close, restart Outlook, and send again.
  3. Send/Receive to clear the Outbox. Open the Send / Receive tab and click Send/Receive All Folders (or press F9). If the stuck message won't move, open the Outbox, open the message, close it, and it will usually flush on the next send.
  4. For Google Workspace (GWSMO) accounts, rebuild the profile. If the account is a Google Workspace account synced with the Google Workspace Sync tool, a fresh Outlook profile almost always clears 0x8004010b. Close Outlook, then from the Start menu choose Google Workspace Sync > Set up a Google Workspace Sync user, sign in and click Create profile; GWSMO then re-downloads your mail from Google, so nothing on the server is lost. If you have any local-only PST folders (archive folders that live only on your PC), back that PST up first before you switch profiles.

Before you delete anything

The safe way to rebuild a profile

Creating a new mail profile is a standard, safe step — but only your mailbox on the server re-downloads automatically. Anything that lives only on your computer (old Archive or Personal Folders PST files) does not come from the server and won't come back on its own.

So before you add a new profile: in File > Account Settings > Data Files, note where each PST lives, close Outlook, and copy those .pst files somewhere safe (Documents or a USB stick). One tip: for a Microsoft 365 or Outlook.com account you'd re-add the account from inside Outlook's own sign-in prompt (modern login), not the old Control Panel dialog — but for Google Workspace the GWSMO tool handles it. If you're at all unsure which files are local-only, don't guess — this is exactly the kind of thing we'll check for you remotely so nothing gets lost.

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// GOOD QUESTIONS

Frequently asked

What does "sending reported error 0x8004010b" mean in Outlook?

It means Outlook can't write your outgoing message into its data file. Usually the wrong data file is set as the default store, the mailbox is full, or a Google Workspace profile has become corrupted. It's a settings problem, not lost email — the message just waits in your Outbox until it's fixed.

Will fixing 0x8004010b delete my emails?

No. Setting the correct default data file and clearing the Outbox don't touch your mail. Even creating a new profile is safe for mailbox mail — Outlook re-downloads it from the server (Exchange, Microsoft 365, IMAP or Google Workspace). The only thing to protect is any local-only PST archive, which you should back up before switching profiles.

Why do I get 0x8004010b with Google Workspace and Outlook?

Google Workspace accounts synced with the Google Workspace Sync tool (GWSMO) store mail in a local PST. If that profile gets tangled, sends fail with 0x8004010b. The reliable fix is a fresh profile made with Start > Google Workspace Sync > Set up a Google Workspace Sync user — GWSMO then re-downloads your mail from Google.

How do I set the correct data file as default in Outlook?

Go to File > Info > Account Settings > Account Settings, open the Data Files tab, click the file for the account you send from, and click Set as Default. Restart Outlook and send again.

My mailbox says it's full — how does that cause 0x8004010b?

When the mailbox behind your default data file is at its storage limit, Outlook can't write new items and the send fails. Empty Deleted Items, clear large Sent items, and (for Google Workspace) check your Google storage. Once there's headroom, the Outbox usually clears on the next Send/Receive.

Can 365 Techies fix Outlook error 0x8004010b remotely?

Yes. We connect with your permission (we phone first, you watch the whole session, and access ends the moment we're done), point Outlook at the correct data file, check your mailbox and profile, and get your email sending — usually within minutes. Windows and Android only. Call 01202 775566.

// Still stuck?

Still stuck in the Outbox?

We'll connect remotely (you watch the whole time, we phone first, access ends the moment we're done), point Outlook at the right data file and get your email sending again — usually within minutes.

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