Hello Mfellner,
If you're not using an application like Outlook or Thunderbird which contains the functionality for this issue (typically called out of office messages). Then you can use the option provided in the Cpanel under MAIL. The option is called an Auto-responder. Here's our educational channel article on this option:
Setting an Autoresponder in the Cpanel
This will help you setup the parameters for you. If you have any further questions, please contact technical support or leave a comment at the bottom of the page.
Regards,
Arnel C.