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 of error, generally user not able to send the email because the 0x800ccc0b error in Outlook generally occurs due to wrong SMTP server details.
Error Message: An unknown error has occurred. Account: ‘ firstname.lastname@example.org’, Server: ‘mail.yourdomain.com’, Protocol: SMTP, Port: 25, Secure (SSL): No, Error Number: 0x800CCC0B
Look at the simple solution to fix the send/receive Outlook error 0x800ccc0b.
Click on the “Account Settings” under the “Tools” menu.
In the new account setting window, click on the “Email” and make a double click on the email address by which you are not able to send emails.
Through double click other pop-up window will appear, now click on “More Settings” buttons.
Go to the Outgoing Server tab and select the “My outgoing server (SMTP) requires authentication” checkbox.
My outgoing server (SMTP) requires authentication.
Useful link: go for Microsoft Outlook 2016 download here.