Sending’ reported error (0×800CCC65) : ‘Your outgoing (SMTP) e-mail server has reported an internal error. If you continue to receive this message, contact your server administrator or Internet service provider (ISP). The server responded: 503 valid RCPT command must precede DATA’

Solution : In Outlook, select Tools > Options > Email Accounts > More settings > Outgoing server — check the box marked ‘My outgoing server

(SMTP) requires authentication.’