If your Mac Mail Outbox is stuck, the email in it is one Apple Mail tried to send and couldn't. Usually the outgoing (SMTP) server rejected your password, the connection dropped, or the message was too large. Check the account's status icon, fix the outgoing server settings, then send the message again or move it to Drafts.
What does Outbox mean in Apple Mail?
The Outbox is a temporary mailbox for messages Mail couldn't send. If a message sits in the Outbox and isn't sending, Mail couldn't deliver it. When a send fails, Mail shows this alert: "This message could not be sent. It will remain in your Outbox until it can be sent." The message waits there until you fix the problem and send it again, edit it or delete it.
The Outbox only appears in the sidebar while something is in it. Two other features look similar but mean something different:
- Send Later is the mailbox for messages you scheduled. They aren't stuck. Mail sends them at the time you picked, but only if the Mac is on and online at that time.
- Undo Send shows at the bottom of the sidebar for 10 seconds after you click Send. You can change that delay in Mail > Settings > Composing > Undo send delay. Until the time runs out, the message hasn't left your Mac.
Why emails get stuck in Apple Mail
When the Outbox won't clear, Mail and your mail provider have stopped agreeing on something. The usual causes:
- Your password changed on Gmail, iCloud or Outlook and Mail still has the old one, or the provider now wants a different kind of sign-in.
- Patchy Wi-Fi or a filter on your network interrupts the connection, so Mail can't connect to the server.
- Mail or the account is offline. A VPN or security software that monitors your network can make Mail think you're offline.
- You've hit a provider limit: messages per day, maximum message size or a full mailbox. To see how much storage you're using, Control-click the account's inbox and choose Get Account Info.
- The attachment is bigger than your provider allows. Mail Drop exists for exactly this (step 7).
- One recipient address is wrong. Some mail servers won't send a message at all if even one address is incorrect.
How to clear your Outbox
Work through these in order, starting at step 1. Password and server problems (steps 4 and 5) are the usual cause.
1. Check the connection and the account status
Load any website in your browser to confirm the Mac is online. Then look for a warning symbol or a lightning bolt next to the account's inbox in the Mail sidebar, or in the upper-right corner of the Mail window. Click it to read what Mail reports. If it says the network is offline or Mail can't connect to the server, check for a VPN or other software that interacts with your network connection, and turn it off while you test.
2. Use the options Mail offers when sending fails
When a message can't be sent, Mail opens a panel with these buttons:
- Edit Message reopens the email so you can fix an address or remove a large attachment.
- Edit SMTP Server List opens the list of outgoing servers set up in Mail.
- Connection Doctor tests your connections (step 3).
- Try Later leaves the message in your Outbox until it can be sent.
If you have more than one account, the panel also lists other outgoing servers. You can select one and click Try With Selected Server to send the message through that account instead.
3. Run Connection Doctor
Choose Window > Connection Doctor. The Mail Connection Doctor window lists each account with its status and details, so you can see which server Mail can't reach. Click Check Again after you change a setting. If one account's outgoing server fails, that's the account to fix in the next two steps.
4. Check the outgoing server settings
Choose Mail > Settings, click Accounts, select the account, then click Server Settings. Under Outgoing Mail Server (SMTP), check the account name and password. If you changed your password with Gmail, iCloud or Outlook recently, enter the new one here.
Leave "Automatically manage connection settings" turned on unless your provider gave you a specific port. If it did, turn the option off and enter the port and the "Use TLS/SSL" setting exactly as your provider lists them. For an iCloud account, Apple says to choose iCloud as the outgoing mail account in this same tab.
If nothing sends at all, even with an empty Outbox, see our guide to Apple Mail not sending emails.
5. Re-enter your password or app-specific password
If your account uses 2-step verification, your normal password may not work in Mail. Some providers want an app-specific password for Mail, others want you to sign in through their own page. Sign in to your webmail first to make sure the password itself is right. If Mail keeps rejecting it, follow our fix for unable to verify account name or password.
6. Move or delete the stuck message
Sometimes the problem is the message itself.
- Click Outbox in the sidebar. It only appears when a send has failed.
- Drag the stuck message to Drafts, or delete it.
- Send a short, text-only email to yourself. If it goes through, open the draft and send it again.
7. Send large files with Mail Drop
If the message carries a big attachment, Mail Drop can send it. Files over your provider's size limit are uploaded to iCloud and kept for up to 30 days, and they don't count against your iCloud storage. You need to be signed in to your Apple Account. To turn it on, choose Mail > Settings > Accounts, select the account, click Account Information and select "Send large attachments with Mail Drop".
8. Quit and reopen Mail
Quit Mail, open it again and try sending. If Mail won't respond, press Option-Command-Esc, select Mail and click Force Quit.
9. Remove the account and add it back
This is Apple's last-resort fix. Sign in to your webmail first and check that your mail is stored on the server. Then remove the account in Mail > Settings > Accounts and add it again, choosing the right provider for your address.
Email stuck in the Outbox on iPhone or iPad
Mail on iPhone and iPad has an Outbox too. Apple's steps:
- In Mail, go to your list of mailboxes.
- Tap Outbox. If you don't see an Outbox, the email was sent.
- Tap the email and check that the recipient's address is correct.
- Tap Send.
If you see an Undo Send button in your inbox or mailbox list, the message hasn't gone yet. If it still won't send, delete the account and add it back: go to Settings > Apps > Mail > Mail Accounts, tap the account, then tap Delete Account. Check on your provider's website first that your email is stored there, because deleting the account can remove downloaded mail from the device.
With iCloud Mail, Apple also suggests turning off any VPN, restarting the device and checking that you haven't reached your iCloud storage or sending limits. Large attachments can go by Mail Drop instead.
Using Outlook for Mac instead?
Outlook for Mac has its own Outbox, and the Apple Mail steps above don't apply to it. Microsoft's Outlook for Mac help page says to check that you're connected to the internet first, then whether the message has an attachment that's too large to send. The same page shows how to update Outlook: Help > Check For Updates.
For setup, settings and other fixes on both devices, see our Apple Mail guide.
Sources
- Apple: If you can't send or receive email on Mac
- Apple: If you can't send email on your iPhone or iPad
- Apple: If iCloud Mail isn't working
- Apple: How to force an app to quit on Mac
- Mail User Guide: Send email messages
- Mail User Guide: Send attachments
FAQ
What does Outbox mean in Apple Mail?
The Outbox holds messages Mail tried to send but couldn't. Mail tells you: "This message could not be sent. It will remain in your Outbox until it can be sent." Fix the cause, usually the outgoing server or the password, then send the message again.
Why are my emails stuck in the Outbox on my Mac?
Most often the outgoing server rejected your password, the Mac or the account was offline (a VPN can cause this), the message was over your provider's size limit, or one recipient address was wrong. Window > Connection Doctor shows which account has the problem.
How do I delete an email stuck in the Outbox?
Click Outbox in the Mail sidebar, select the message and delete it. If you want to keep it, drag it to Drafts instead and send it again once the problem is fixed.
Will emails in the Outbox send eventually?
If the problem was temporary, such as a dropped connection, the message stays in the Outbox until it can be sent. If the cause is a wrong password or server setting, it won't go until you fix that. Then open the Outbox and send it again.
Why don't I see an Outbox in Mail?
Mail only shows the Outbox while it holds a message that couldn't be sent. On iPhone, Apple says that if you don't see an Outbox, the email was sent. Messages you scheduled wait in the Send Later mailbox instead.
How do I fix an email stuck in the Outbox on iPhone?
Go to your list of mailboxes, tap Outbox, tap the email, check the recipient's address and tap Send. If it still won't send, delete the account in Settings > Apps > Mail > Mail Accounts and add it back, after checking that your mail is on the provider's server.