An unknown error has occurred SMTP Error 0x800CCC0B

If you are getting 0x800ccc0b error while sending an email then you should first check the server configuration info in MS-Outlook. In this case, generally user not able to send the email because the 0x800ccc0b error in Outlook generally occurs due to wrong SMTP server settings. You may experience when you receive or send an email message in Outlook. This guide will show you how to fix an unknown error has occurred SMTP Error 0x800CCC0B.

RECOMMENDED: Fix this issue in 3 simple steps. Takes only 2 minutes.
1) Download repair utility.
2) Install program and click Scan button.
3) Click Fix Errors button when scan is completed.
4) Restart your computer.

  • Error Message: An unknown error has occurred. Account: ‘’, Server: ‘’, Protocol: SMTP, Port: 25, Secure (SSL): No, Error Number: 0x800CCC0B
  • Task ‘machine.domain.xom – Sending and Receiving’ reported error (0x800CCC0B): ‘Unknown Error 0x800CCC0B’

Warning : Before making any changes in your computer, I suggest you to create a System Restore point  so that you can restore back your computer to previous working state if something goes wrong. 

How to fix An unknown error has occurred SMTP Error 0x800CCC0B?

Step 1: Make sure that your Outlook email account settings are correct.

  1. Click on the “Account Settings” under the “Tools” menu.

Fix An unknown error has occurred SMTP Error 0x800CCC0B2. Click on the “Email” and make a double click on the email address by which you are not able to send emails.

Fix An unknown error has occurred SMTP Error 0x800CCC0B3. Through double click other pop-up window will appear, now click on “More Settings buttons.

Fix An unknown error has occurred SMTP Error 0x800CCC0B4. Go to the Outgoing Server tab and select the “My outgoing server (SMTP) requires authentication” checkbox.

Fix An unknown error has occurred SMTP Error 0x800CCC0B

Quick Info: Go through the below information to check email account settings in outlook.

We have listed some major Internet Service Providers settings (for manual configuration of Outlook).

We recommend that you contact your Internet service provider (ISP) for information about the exact incoming and outgoing mail server names and settings that you should use when you configure your Internet email account in Outlook. The list provided here contains information only for few Internet service providers in the United States and may not be up to date.

Incoming Mail (POP3) server names and settings:

Provider Name Server Name Port SPA SSL AuthRequird
AT&T Yahoo 995 OFF ON ON
Charter 110 OFF OFF ON
Comcast 995 OFF ON ON
Cox pop.[insert region] 110 OFF OFF OFF
Gmail 995 OFF ON ON
Juno 110 OFF OFF OFF
Microsoft Live 995 OFF ON ON
Netscape 110 OFF OFF ON
Netzero 110 OFF OFF ON
Pacbell 995 OFF ON ON
PeoplePC 110 OFF OFF ON
Qwest pop.[enter state ID] 110 OFF OFF OFF
Rogers 110 OFF OFF ON
SBCGlobal 995 OFF ON ON
Swbell 995 OFF ON ON
Verizon 110 OFF OFF ON
Yahoo 110 OFF OFF OFF

Outgoing Mail (SMTP) server names and settings:

Provider Name Server Name Port SPA AuthRequired Encryption
AOL 587 OFF ON None
AT&T Yahoo 465 OFF ON SSL
Charter 25 OFF ON None
Comcast 587 OFF ON TLS
Cox smtp.[insert region] 25 OFF OFF None
Gmail 587 OFF ON TLS
Juno 587 OFF OFF None
Microsoft Live 587 OFF ON TLS
Netscape 25 OFF OFF None
Netzero 25 OFF ON None
Pacbell 465 OFF ON SSL
PeoplePC 587 OFF ON None
Qwest pop.[enter state ID] 25 OFF OFF None
Rogers 587 OFF ON None
SBCGlobal 465 OFF ON SSL
Swbell 465 OFF ON SSL
Verizon 25 OFF ON None
Yahoo 25 OFF OFF None

Step 2: Check your antivirus manufacturer’s website for additional suggestions or Disable the antivirus software. And Disable the firewall in router.

If you found outlook is working fine after disable the antivirus software, highly recommended to uninstall the same using their removal tool and reinstall it.

List of manual antivirus uninstallers

    1. Click the link associated with the antivirus software currently installed on your system and follow the prompts or instructions on the website.
    2. Once uninstallation is complete, you will need to restart your computer.






CA Antivirus see Total Defense Anti-Virus
Comodo Internet Security
Cyber Defender Early Detection Center


Dr. Web
(Only registered Dr. Web users can access support content)




FRISK F-PROT Antivirus for Windows


G Data


K7 Total Security




Microsoft Security Essentials


Norman Virus Control/Norman Security Suite
Norton (Symantec)
Norton Security Scan


Panda Cloud Internet Protection
Pareto Logic


Spybot Search & Destroy


Total Defense Anti-Virus (formerly CA Anti-Virus)
Trend Micro
Trend Micro Titanium
Trend Micro Worry-Free Business Security Agent


Vipre (Sunbelt Software)


Windows Defender
Windows Live OneCare
Windows Security Essentials


Zone Alarm

I hope that the above steps helps you to fix the SMTP Error 0x800CCC0B. If above steps did not help, you may have to create new outlook profile and reconfigure email settings. In addition, try creating new Windows user account as well. Hope this will help you to fix the issues. Or you have to contact your ISP for further assistance. For further support, leave comments or ask more on Forum.

Arun Prabhakar

Arun Prabhakar immensely interested in following Windows and other technology developments. Being passionate Windows blogger, he loves to help others on fixing their computer issues.