This error was getting thrown after every backup my system does. BrightStor used to send me emails when it finished a backup job but at some point in time it started failing.
The simple fix for this is to add in a hosts entry for the SMTP server. Even though I specified an IP address for my SMTP server this fix worked.
To add in a hosts record open Notepad or whatever text editor you love and then open the file "C:\Windows\System32\Drivers\Etc\hosts". Notice there is no extension on this file.
If you have your \Windows directory located on a partition other than "C:" use "%windir%\System32\Drivers\Etc\hosts".