Can't Send Email in Outlook (Error 0x800CCC0F and Similar Fixes)
Outlook showing error 0x800CCC0F or refusing to send emails? These steps cover the most common causes — wrong SMTP settings, firewall blocks, and corrupted profiles — and how to fix each one.
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Error 0x800CCC0F means Outlook lost its connection to the outgoing mail server mid-send. A handful of related errors (0x800CCC0E, 0x800CCC19, 0x8004210B) all point to the same family of problems: a network hiccup, a misconfigured outgoing server, or something on your PC blocking the connection. Here is how to work through them.
1. Check Your Internet Connection First
Open a browser and load any website. If pages load fine, your internet is not the issue. If nothing loads, restart your router and try again before continuing.
2. Verify Your SMTP Server Settings
In Outlook desktop, go to File > Account Settings > Account Settings, select your email account, and click Change. Then click More Settings > Outgoing Server and Advanced. Common correct settings:
- Gmail: smtp.gmail.com, port 465 (SSL) or 587 (TLS/STARTTLS)
- Outlook.com / Hotmail: smtp-mail.outlook.com, port 587, STARTTLS
- Yahoo: smtp.mail.yahoo.com, port 465 (SSL)
Make sure My outgoing server (SMTP) requires authentication is checked, and that it uses the same settings as your incoming server.
3. Temporarily Disable Your Antivirus Email Scan
Many antivirus programs intercept outgoing email to scan it. This can break Outlook's connection. Look in your antivirus settings for an Email Protection or Mail Shield option and disable it temporarily. If email sends successfully after that, add Outlook as an exception rather than leaving protection off permanently.
4. Try Sending in Safe Mode
Close Outlook. Hold Ctrl and click the Outlook icon in the Start menu (or run outlook.exe /safe). If email sends in Safe Mode, a faulty add-in is the culprit. Go to File > Options > Add-ins, set the dropdown to COM Add-ins, click Go, and uncheck add-ins one at a time to find the offender.
5. Create a New Outlook Profile
A corrupted profile can cause persistent send errors. In Control Panel > Mail > Show Profiles, click Add to create a new profile, then add your email account to it. Set it as the default and restart Outlook.
If none of these steps resolve the issue, ask us with your exact error code and email provider for more targeted help.
Frequently asked questions
Does error 0x800CCC0F always mean a server problem?
Not always. It most often means Outlook dropped the connection to the outgoing server, which can be caused by your local firewall, antivirus software, a bad add-in, or incorrect SMTP settings — not necessarily a problem on the server itself.
My settings look correct but I still get the error. What else can I try?
Try switching the SMTP port. If you are using port 25, change it to 587 with STARTTLS or 465 with SSL. Port 25 is blocked by most internet providers for home connections to prevent spam.
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