If you use Outlook as an e-mail program your client, and experiencing the following error when sending e-mail using SMTP protocol;
"An unknown error has occurred. Account: 'emal@yourdomain.com', Server: 'mail.yourdomain.com',
Protocol: SMTP, Port: 25, Secure (SSL): No, Error Number: 0x800CCC0B "
Please make sure the following things to solve the problem;
Make sure the configuration e-mail account
Display Name: Your Name
E-mail address: E-mail (full with@yourdomain.com)
My incoming mail is a: POP3 Server
Incoming mail (POP3, IMAP or HTTP) server: mail.yourdomainname.com
Outgoing mail (SMTP) server: mail.yourdomainname.com
Account name: full email address
Password: password
Make sure the option 'Log on using Secure Password Authentication (SPA)' is NOT checked (unchecked)
Click your account and select Properties.
In the Server tab make sure that you check the option 'My server requires authentication' CHECKED. Click Apply