Roadrunner / RR Mail is a Web-based email client. SMTP server is the backbone of your email service. It uses the Internet to send emails to your clients. If you have an SMTP server that is not working properly, you may experience issues with sending emails.  If your SMTP server is not working and you are getting an error message, the most likely cause is that the server has been infected with a virus. You can find out what version of the SMTP server you have by going to the control panel and looking for it there. If it does not exist, then you will need to download a new version. If it does exist, then go ahead and open up your email clients, such as Outlook or Thunderbird, and check out what kind of information is coming in through your email program. If it seems like it's just junk mail or spam coming in, then try using another server instead of your current one. If you still have issues after trying this method, then I would recommend contacting your internet service provider (ISP) in order to see if they can fix whatever problem may be causing this issue.