Check to see that the following file exists on the WEB server (NOT REWS)

c:\program files\blackbaud\bbappfx\vroot\bin\Blackbaud.AppFx.EmailServices.Server.dll

If the file does not exist, complete the following steps on the web server
  1. Open Control Panel
  2. Open Programs and Features
  3. Right Click the listing for "Blackbaud"
  4. Choose Change\Uninstall
  5. When the Blackbaud Installer starts and prompts you, choose "Modify\Repair"
  6. Once the Modify\Repair is complete, attempt to send the email again.

If the issue is still not resolved, please contact Blackbaud Support