I cannot send emails anymore because they remain in the Outbox

BrazzFound 0 Reputation points
2026-11-04T11:06:44.2733333+00:00

How to fix the issue when emails remains in the Outbox instead of being sent ? On outlook app for Mac.

Outlook | MacOS | New Outlook for Mac | For home
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  1. AI answer

    2026-11-04T11:07:02.88+00:00

    For Outlook for Mac, try these checks in order:

    1. Check whether Outlook is offline.
      • Open the Tools tab.
      • Move the slider to Online.
      • If the app is online and mail is working normally, the Outbox should disappear after queued messages are sent.
      • This Online/Offline toggle is not available in New Outlook for Mac.
    2. If a message is still sitting in Outbox, stop sending and edit or remove it.
      • On the Tools tab, move the slider to Offline.
      • Open the message from Outbox.
      • Edit it or delete it, then try sending again after going back online.
      • This toggle is also not available in New Outlook for Mac.
    3. Verify the outgoing mail settings.
      • In Outlook for Mac, go to Tools > Accounts.
      • Select the account in the left pane.
      • Check the Outgoing server value and make sure it is correct.
      • If the network or ISP blocks the current SMTP server, use an alternative SMTP server if one is provided by the mail provider or network administrator.
    4. Verify account credentials and account configuration.
      • Go to Tools > Accounts.
      • Select the account.
      • Confirm the email address, user name, and password are correct.
      • Some accounts require special settings such as SSL or non-default ports.
    5. If the issue happens only on one network, check for network restrictions.
      • A firewall or proxy on the current network can block connections to the outgoing mail server.
      • If required, configure the mail proxy server in macOS System Preferences using the settings provided by the network administrator.
    6. If sending works in Outlook on the web or on mobile but fails only in Outlook for Mac, and the error is "Unexpected data was encountered", the mailbox folder hierarchy may be corrupted.
      • In that case, the Sent Items folder may no longer be recognized correctly.
      • The documented fixes are to reset or rename the Outlook folders by using Outlook for Windows, Outlook Web App, or an administrator cmdlet.
      • A self-service option is to sign in to Outlook Web App, go to Settings > Options > General > Region and time zone, change the language, select Rename default folders so their names match the specified language, save, then restart Outlook for Mac.

    If the issue started recently and only affects Outlook for Mac, these steps are the most directly supported for Mac: check online status, verify account credentials, verify outgoing server settings, and rule out firewall or proxy blocking.

    AI-generated content may be incorrect. Read our transparency notes for more information.

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  2. Lychee-Ng 30,320 Reputation points Microsoft External Staff Moderator
    2026-11-05T08:29:46.2+00:00

    I understand how frustrating this is, BrazzFound.

    The AI suggestions actually covered the main initial checks, so have you tried them out yet? And what's the outcome? If the issue still persists, so to make sure I'm not sending you through more unnecessary self-troubleshooting, can you clarify a few things for me?

    • What type of email account are you using: Outlook.com, Gmail, iCloud, or another provider?
    • Are all emails getting stuck in the Outbox, or only certain ones?
    • Do you see any error message or error code returned when you try to send?
    • If you sign in to the same account through its webmail, can you send successfully there?

    So if you haven't tested it yet, the last point above is particularly useful. For example, if you're using Outlook account, then go to the web version (Outlook.live.com) and try it out. If you can send normally through webmail, we can focus on the Outlook app itself. If sending also fails, the issue is more with the account or mail service.

    Another thing to note is that there have been a few reports from other community members about outgoing emails failing to send. Although I can't confirm if it's even related to your case, the similarity is worth considering. If this is urgent and you'd like to get it resolved directly, you can also consider reaching out to Microsoft Support:

    1. In Outlook, select Help > describe your issue > follow the recommendations.
    2. If nothing changes, scroll down to Still need help? and select Yes.
    3. If that doesn't connect you with an agent, go to Contact Us - Microsoft Support   
    4. Enter "contact" > Get Help > scroll down and click Ask our Support Assistant
    5. If the issue persists, specifically state in the chat box that you need direct help.   
    6. The Contact Support button should appear > select the chat in browser option.

    User's image

    Note: The support contact team only works at certain times, so if the last window shows that it's unavailable, try opening it again the next day. If you prefer phone support, you can leave a phone number. This way, they can call you and help you. If you don't see chat option, choose another category and ask to escalate.

    Since Microsoft Q&A is just a user-to-user support forum, with no access to internal or backend Outlook system. If this ends up an account/server-side issue, it'd need to be investigated by Microsoft Support.

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