- Go to system preferences and click [Internet Accounts]
2. Click the [+] symbol, and then [Add other accounts] 
3.Enter your name, email address and password then click [Sign in]
4. At this point you will most likely get the error “Unable to verify account name or password”, fill in the rest of your details and click [Sign In] again. 
5. Click [Done] 
6 Return to Mail, and select [Mail] [Preferences] 
7 Open the [Server Settings] tab. 
8 Uncheck “Automatically manage connection settings” then set the port to “465” and the authentication type to “Password” then click [Save] 
9 Once verified you should be able to send and receive email. 