Related to: Email sending/SMTP problem at client side.  

"Sending' reported error (0x800CCC65) : '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'"


 The most common reason for this issue is that your mail client fails to authenticate to the server. Generally, this is caused by the email client’s (for example MS Outlook) SMTP authentication not switched on.  

 This reason could be resolved by following;  

  1. Pop before smtp -- check your email for new mail before trying to send email. This adds your IP address to a relayhosts file and allows any email to be sent from that IP address for up to 30 minutes. After 30 minutes you have to authenticate again.
  3. P  Configure your email client to authenticate automatically by checking the "my server requires authentication" box in your email configuration. You will be able to send mail without having to "pop" your mail box first.    

 Another possible reason for the issue is an Antivirus or Firewall software which is checking your outgoing mail connections. In case you have set properly your mail client as explained above and the issue persists, please turn off the antivirus and the firewall software you have installed on your local computer and try sending out e-mails again.