This article explains why an email may be stuck in Outlook and provides methods to force it to send or delete such a message from the Outbox of Outlook 365, 2021, 2019, 2016, 2013, and earlier versions.

Emails may remain in the Outbox for several reasons. If you wish to skip directly to the quick solutions for deleting a stuck email, jump to the section on 4 quick ways to delete an email stuck in Outlook Outbox. Otherwise, continue reading to understand the causes and potential fixes.

Attachments larger than the limit set by your mail server can prevent emails from being sent. In such cases, you can either delete the attachment or move the email to the Drafts folder to resize or remove it.

To delete a stuck email, first activate the Send/Receive tab and click Work Offline. This prevents Outlook from attempting to send emails currently in the Outbox. Next, switch to the Outbox, right-click the message, and select Delete.

To resize or remove the attachment, put Outlook in Offline mode as explained earlier, go to the Outbox, drag the stuck message to the Drafts folder, and make the necessary changes. Alternatively, right-click the email, select Move, and choose Other Folder > Drafts.

Note: If you encounter the error "Outlook has already begun transmitting this message" when trying to delete or move a stuck email, allow some time for Outlook to finish sending. If it remains stuck, refer to the guide on deleting a hanging email.

Tips: Instead of sending large attachments, upload them to a local network share and include a link in the email. Alternatively, use cloud-based services like Dropbox or SkyDrive when you're away from your main network.

Opening or viewing the Outbox

When an email is opened or viewed while it's in the Outbox, it may be marked as read and won't be sent. The email's title will no longer appear in bold, indicating it's stuck.

This behavior is often due to certain Outlook add-ins, such as Business Contact Manager (BCM), Social Connector add-in, Xobni, iTunes Outlook Addin, iCloud add-in, and others.

While uninstalling or disabling these add-ins may help, it’s not always advisable since some might be essential for your workflow.

A simple workaround is to drag the stuck email from the Outbox to another folder, like Drafts, open the email in that folder, and click Send. For more details, refer to the guide on resending a stuck email.

In the future, avoid checking the Outbox when there are pending messages.

Incorrect email account password

Symptom: You’ve created a new or modified an existing email account, or recently changed the password on your Internet email account.

Verify your password by logging into your email account via the web.

If you’ve updated your password on platforms like Gmail or Outlook.com, update it in Outlook as well:

1. Navigate to the File tab > Info, and then select Account Settings twice.
2. In the Account Settings dialog, select the account needing a password change and click Change....
3. Enter the new password and click Next > Finish.

Improper authentication with the mail server

First, verify your email account settings:

1. In Outlook 2016, 2013, and 2010, go to the File tab and click Account Settings twice, similar to the password-changing process. In Outlook 2007, navigate to Tools menu > Account Settings > Email. For Outlook 2003 and earlier, go to Tools > E-mail accounts > View or Change existing accounts.

   Double-click the account, then click Tools menu > Account Settings > Email.

2. Switch to the Outgoing server tab and confirm your settings align with those recommended by your email provider. Remember that some providers may require a password for sending emails. Do not select "Require Secure Password Authentication" unless explicitly instructed by your mail server.

3. On the Advanced tab, check the Outgoing Server port number:

   • Typically, SMTP uses port 25, though many providers now prefer port 587.
   • Encrypted SSL connections use port 465.
   • POP accounts generally operate on port 110.
   • IMAP email accounts use port 143.

   For Gmail users:

   • If using Gmail as a POP account, input 995 for the "Incoming server (POP3)" field and 465 for the "Outgoing server (SMTP)". Select the option "This server requires an encrypted connection (SSL)".
   • If using Gmail as an IMAP account, input 993 for the "Incoming server (POP3)" field and 587 for "Outgoing server (SMTP)". Ensure "This server requires an encrypted connection (SSL)" is checked.

For detailed instructions on setting up Gmail accounts, refer to the article: Configuring the Outlook Gmail settings.

Outlook set to offline or mail server down

Symptom: You cannot send or receive emails but can browse the web.

Check your connection status by looking at the Status Bar in the bottom-right corner of the Outlook window. If offline, you'll see a notification.

To reconnect, go to the Send / Receive tab, Preferences group, and click the Work Offline button to toggle it off.

If Outlook is online but messages remain stuck, ensure your mail server is operational. Open your internet browser; if it works, your mail server is likely down. Either notify your IT personnel or take a break until the issue is resolved.

No default email account

Symptom: You can reply to emails but cannot send new ones.

One possible cause is configuring your email account using a pre-set script from your admin.

Identify the default account by opening the Account Setting dialog. In Outlook 2016, 2013, and 2010, go to File > Account Settings. For Outlook 2007 and older, follow the earlier instructions.

The default account is marked with a note and a tick beside it, as shown below.

If no account is set as default, select the desired account by clicking on it and then click Set as Default.

Programs accessing Outlook data files (.pst or .ost)

Symptoms: Email sending initially works but then halts, leaving messages stuck in the Outbox. You may also encounter errors such as An unknown error has occurred. 0x80040119 or 0x80040600.

To address this, try restarting Outlook:

1. Exit Outlook.
2. Use Task Manager to ensure no lingering outlook.exe processes remain. Refer to the guide on removing hanging Outlook processes.
3. Restart Outlook.

You can also use the Inbox Repair Tool to scan and fix errors in the .pst file. The tool’s location varies based on your OS. Follow Microsoft’s instructions for different Windows versions: How to resolve "An unknown error has occurred" error.

If the problem persists, disable or uninstall the problematic software.

Antivirus or antispam software interfering with outgoing emails

Symptoms: Similar to the previous point.

If antivirus software is causing issues, first check the manufacturer’s website for updates and community forums for solutions. Disabling email scanning may help. While this feature is optional and mostly for extra security, even without it, modern antivirus programs will still protect your system by scanning incoming files.

Additionally, try setting a timeout in Account Settings > More Settings > Advanced tab.

If the issue continues, consider switching to an alternative antivirus program. However, weigh the risks carefully—going without antivirus protection leaves your system vulnerable to viruses and malware.

I hope this article helps you effectively manage emails stuck in your Outbox. I certainly gained some valuable insights while writing it!

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