Why Is Apple Mail Email Stuck in Outbox? Know the Reason!

Are you wondering why your Apple Mail email stuck in Outbox? The stuck email in Apple Mail is one of the most widely reported Mac issues. It’s usually caused by a network glitch, authentication failure or a large attachment clogging the queue. In the vast majority of cases, the situation will result from some temporary network problems or from a large email preventing other messages from getting out.

Among the quickest solutions, one could mention simply checking the outgoing mail server settings or removing the one huge, problematic email from the Outbox.

Why Do Messages Get Stuck Inside Apple Mail Outbox?

If one or more emails are still sitting in the Outgoing folder, then it is most likely an error occurring between Apple Mail and your ISP/email service provider. Here are some of the causes that are responsible for the Apple Mail email stuck in the outbox problem.

• Account Authentication problems: If you change the password of your Gmail, iCloud or Outlook account and you forget to inform it to the Apple Mail application, the problem arises, since your application will not be able to authenticate correctly and thus a particular email is going to remain trapped within the Apple Mail Outbox.
• Huge Mail Attachments: When sending large email attachments beyond the allowed limits set by the provider, one’s emails will fail to go through. Large file attachments often tend to freeze up the process of sending emails.
• Connection Problems/Server Downtimes: If the Wi-Fi connection is poor, if the ISP limits the data transfer, or even if the server of your email provider is down or temporarily unavailable, this will give rise to connection failures.

How to Fix Apple Mail Email Stuck in Outbox?

If you have been wondering how to fix a stuck email in my Outbox, the following ways could help fix this problem speedily.

Fix 1: Force Quit and Relaunch Apple Mail

Before we go into the advanced fixes that involve checking all the settings, let’s try the simple fix first. Force quit Mac Mail if the emails are stuck or not responding.

• Press Command + Option + Esc to launch Force Quit.
• Choose Mail, click Force Quit.
• Open Mail and try sending once more.

Fix 2: Check if Apple Mail is “Offline”

There will be no sending and receiving if there is no connection with the mail server in the Apple Mail program, which might result in “Apple Mail email stuck in outbox.” Your account might get disconnected from the internet manually or due to any kind of connectivity issue.

1. Launch Apple Mail.
2. Click Mailbox from the menu bar.
3. Click Take All Accounts Online to reconnect.
4. Try sending the emails again.

Check whether the “email stuck in the outbox of Apple Mail” is resolved or not.

If Apple Mail is failing to receive new messages, and the outgoing emails are stuck, check the article Apple Mail not receiving emails for troubleshooting steps.

Fix 3: Delete or Move the Problem Message

Often, a single corrupted email may cause an obstruction for everything else below it in the sending process. Find the oldest or largest hung-up message and remove it.

• Open the Outbox in the Apple Mail sidebar.
• Drag and drop it to the ‘Drafts folder,’ or right-click on it to ‘Delete’ it.
• Try sending a new email to check whether other messages are now sending.
• When you can successfully send other messages again, re-draft and resend the ‘deleted’ item.

Fix 4: Reduce Oversized Attachments

The email provider’s size limit may not be enough to handle large attachments in email and file transfer, resulting in an Apple Mail outgoing email stuck problem. For example, Apple Mail will not successfully send a message if the size exceeds the limit established by your account.

Try the following solutions:

1. Compress in the Finder (right-click a file in the Finder and select Compress.)
2. Upload the file to any cloud storage service like iCloud Drive, Google Drive, or Dropbox, then send a download link in your email.
3. If you can, try to break the file down into smaller attachments and email them as different files.

Fix 5: Verify Apple Mail SMTP Settings to Fix “Apple Mail Email Stuck in Outbox”

A very common cause of email sending failure is the wrong or maybe the disconnected SMTP settings. Gmail, MS Outlook, & other such email service providers need proper authentication for the outgoing mail. You can follow the steps given below to perform this process:

1. Open Apple Mail.
2. Go to Accounts.
3. Proceed by selecting Server Settings.
4. Check if the Outgoing Mail Server (SMTP) has been marked as offline.
5. Update your password if it has been changed recently.
6. You have to confirm that the authentication settings are right.

Reviewing such settings usually resolves the Apple Mail email stuck in the Outbox Issue.

Fix 6: Update macOS Version & Apple Mail

The problems in the Outbox might be outside your account. After following the above steps, if the mail remains in the Outbox, check for any macOS update:

• Click the Apple menu>System Settings,
• Then General>Software Update.
• Download any updates available.
• Apple is always rolling out new fixes for mail-in point updates.

macOS (13.x Ventura and 14.x Sonoma) has also suffered from such a sync problem with mail, which was resolved by point updates.

Fix 7: Rebuild the Apple Mail Envelope Index 

A corrupted envelope index is a common, obscure cause of stuck outbox messages that none of the other solutions seems to fix.

The issue: The email message info is stored in an “Envelope Index” database file. The index gets corrupted, and Mail is unable to track sent/unsent mail, so mail hangs forever in the Outbox, although the server settings are set up correctly.

Steps to Rebuild the Envelope Index to fix “Apple Mail email stuck in outbox”:

1. Quit the Apple Mail application totally (Command + Q).
2. Open Finder and use Command + Shift + G.
3. Type: ~/Library/Mail/V10 (the number after V is likely to vary – V9, V8, whatever appears).
4. Find the file named Envelope Index and save it to the Desktop as a backup.
5. Reopen Apple Mail. It will rebuild the index from zero (it may take a few minutes, depending on your mailbox size).
6. When the rebuild is finished, try to see if the stuck message is working.

Update: The rebuild is non-destructive. Your mails are stored in individual .emlx files, so nothing will be lost. Just restore the backup file if there are problems.

The corrupt Envelope Index might also create problems while searching emails through the Mail program. In case, if you are unable to search the emails, refer to our guide on how to fix Apple Mail Search not working.

Fix 8: Remove and Re-add the Mail Account

If you have verified that your SMTP settings are correct, try removing and adding your account again.

Steps to Remove and re-add:

1. Navigate to Mail Settings > Accounts.
2. Choose the account and click the minus (-) to remove it from the selection.
3. Confirm the removal if prompted.
4. Click (+) to add another account or the same.
5. Select the provider (if needed: Google, iCloud, MS Exchange, etc.) and sign in.
6. Allow the Mail sync.
7. Now see again whether the Outbox is empty and the mails are being sent as usual.

Note: Deleting an IMAP or Exchange account will not delete any of your mail (it remains on the server). For the POP3 account, you will want to copy any existing mail you wish to keep locally before deleting the account.

However, in case Apple Mail fails to function due to causes other than the Outbox issue, it would be better to use the information about how to fix Apple Mail not working on Mac provided on our website.

Conclusion

In case you wanted to learn more about why the Apple Mail email is stuck in Outbox, some of the main reasons include SMTP authentication configuration problems, network failure or disconnection, oversized attachments, etc. It would be better to use the suggested innovative approach. However, in case the problem still remains, it would be better to choose a safer way to deal with this problem.