Emails Stuck in Outlook Outbox Because They Are Too Large? Fix It

Few Outlook problems are as frustrating as an email that will not leave the Outbox. You press Send, the message sits there, and sometimes it blocks every email behind it. When the cause is a file that is too large, Outlook may try to send it again and again, slowing everything down.

The message itself is rarely lost, and the fix is usually simple once you stop Outlook from retrying. This guide shows you how to free the stuck email, recover its contents, reduce the attachment, and send successfully without hitting your mail server limits again.

Quick Answer

Put Outlook into Work Offline mode, wait a minute, then open the Outbox and delete or move the oversized message to Drafts. Save its attachments to your computer, share large files by link instead of attaching them, and remove the big attachment before sending again. Turn Work Offline off when you are done.

Why Large Emails Get Stuck in the Outbox

Every mail provider sets a maximum message size. Microsoft 365 and Outlook.com commonly allow messages up to around 25MB to 35MB in total, and many company and internet-provider servers set lower limits, often 10MB or 20MB. The limit covers the whole message, not just the attachment.

Attachments also grow when they are sent. Encoding a file for email typically adds about a third to its size. A 20MB video can become roughly 26MB on the wire, pushing a message that looked acceptable over the server limit.

When the server rejects an oversized message, Outlook may keep it in the Outbox and retry. Worse, Outlook cannot always delete a message while it is mid-send, which is why clicking Delete often appears to do nothing. The message is not corrupt. It is simply too big for the path it has to travel. Microsoft lists the current limits in its reference on sending large files with Outlook and using attachment alternatives.

How to Tell Size Is the Problem

• The stuck message has one or more very large attachments, such as videos or uncompressed photos.
• Smaller test emails also stop sending because they are queued behind the big one.
• You see errors mentioning message size, error 0x80040610, or a server timeout.
• Outlook shows Sending Message 1 of 1 for a very long time, repeatedly.
• The same email sent fine after you removed the attachment in a test.

Step 1: Put Outlook in Work Offline Mode

This is the key step that most people skip. You must stop Outlook trying to send before you can move or delete the message.

1. Go to the Send / Receive tab on the ribbon.
2. Click Work Offline. The status bar should show Working Offline.
3. Wait at least one full minute so the current send attempt times out.
4. If the message still will not move, close Outlook completely and reopen it while still offline.
5. Check the status bar again to confirm you are offline before continuing.

If Outlook was closed while a send was stuck, reopening it in offline mode is still the right approach. Do not reconnect yet. Every reconnection restarts the failed send and locks the message again.

Step 2: Move or Delete the Stuck Message

Now that Outlook is offline, the Outbox should release the message.

1. Open the Outbox folder from the folder pane.
2. Try dragging the stuck message into the Drafts folder.
3. If dragging fails, right-click the message and choose Move, then Drafts.
4. If you no longer need the message at all, select it and press Delete.
5. Confirm the Outbox is now completely empty.

Moving to Drafts is better than deleting when you still need the text or the attachments. From Drafts you can edit the message calmly, remove what is too large, and decide how to share the files properly. If the message refuses to move even offline, restart Outlook once more and repeat. In rare cases, starting Outlook in Safe Mode with outlook.exe /safe releases a message held by an add-in.

Step 3: Recover and Reduce the Attachments

With the message safe in Drafts, deal with the real problem: the attachment size.

1. Open the draft and right-click each attachment, choosing Save As to keep a copy on your computer.
2. Check the saved file sizes in File Explorer so you know exactly what you are dealing with.
3. Remove the oversized attachments from the draft.
4. Decide for each file whether it can be compressed, split, or shared by link.
5. Keep the email itself for its text, recipients, and subject.

Photos can usually be resized with little visible loss. Documents with embedded images can be compressed from within their own apps. Videos are the hardest to shrink without quality loss, and they are almost always better shared by link. A useful rule is to keep total attachments under 10MB unless you are certain both your server and the recipient’s server allow more.

Step 4: Send Large Files the Right Way

Email was never designed for very large files. Modern sharing methods are faster, more reliable, and do not clog anyone’s mailbox.

• Share a cloud link: Upload the file to OneDrive, Google Drive, or your company storage, then paste a sharing link into the email.
• Compress first: Put multiple files into a single ZIP file, which also makes downloading easier for the recipient.
• Split archives: For a file that must be attached, some archive tools can split it into smaller parts, but confirm the recipient can recombine them.
• Resize media: Send web-sized photos instead of original camera files when detail is not critical.
• Use your file transfer service: Many organisations provide an approved large-file service with higher limits and tracking.

OneDrive integrates directly with Outlook, letting you attach a file as a link with permissions you control. Microsoft documents this workflow in its guidance on attaching files and sharing them as links in Outlook. For everyday work, this single habit prevents almost every oversized Outbox problem.

Step 5: Send Again and Clear the Queue

Once the message is fixed, bring Outlook back online carefully.

1. Turn off Work Offline from the Send / Receive tab.
2. Open your edited draft, confirm the attachment list is now small, and click Send.
3. Watch the Outbox. The message should appear briefly and then disappear.
4. Check Sent Items to confirm the message was delivered to the server.
5. Send a small test email to confirm the queue behind it is flowing again.

If a smaller version still sticks, the limit may be lower than you think, or the recipient’s server may be the one rejecting it. In that case you may receive a bounce message explaining the limit. Read it carefully, because it often states the exact maximum size allowed. Our guide to fixing common Outlook send and receive errors helps you interpret those codes when the bounce is not plain English.

Common Mistakes to Avoid

• Trying to delete while Outlook is sending: The message is locked during a send attempt. Always go offline and wait first.
• Resending the same huge attachment: Retrying does not change the server limit. The message will fail every time.
• Forgetting encoding growth: A file that is just under the limit on disk can be over the limit once encoded for sending.
• Deleting without saving attachments: Save the files first. Once the only copy in the draft is gone, recovery is difficult.
• Leaving Outlook offline afterwards: If you forget to turn Work Offline off, no new mail will arrive and you may miss the next problem.

Conclusion

An email stuck in the Outbox because it is too large is freed by one sequence: go offline, wait, move the message to Drafts, save and remove the big attachments, and share large files by link instead. Then reconnect and send the leaner message. Keep attachments small as a habit, and the Outbox will stay clear.

Frequently Asked Questions

What is the maximum email size I can send from Outlook?

It depends on your provider. Microsoft 365 and Outlook.com typically allow around 25MB to 35MB per message, while many company servers allow less. Remember that encoding adds roughly a third to attachment size, so aim well below the stated limit.

Why can I not delete the stuck email from the Outbox?

Outlook locks a message while it is trying to send it, so delete and move commands fail. Switching to Work Offline and waiting a minute ends the send attempt and unlocks the message so you can move or delete it normally.

Will the recipient get part of my stuck email?

No. A message stuck in the Outbox has not been accepted by the server, so the recipient receives nothing. Once you fix the size and send again, they receive one complete copy, not duplicates from the failed attempts.

Can I increase my Outlook sending limit?

For personal accounts, no. The limit is set by the provider. Microsoft 365 administrators can raise the limit within a supported range for their organisation, but the recipient’s server limit still applies to incoming mail.

How do I stop this happening again?

Share files over a few megabytes by cloud link instead of attaching them, compress photos and documents before sending, and check total attachment size before you click Send. These habits prevent nearly all oversized Outbox jams.