You can easily set an Auto Responder from DotNetPanel by following these steps:

Login to DotNetPanel and Click your Package
Next click on Mail and then Accounts
Now you click on the Mail ID on which you want to set Auto Responder
Next, Click on Enable Auto Responder check box. That will enable Auto responder.
Enter the Subject of Auto responder and enter a message in the Message Box.
Click on Save and you’re done.