If you are using Zarafa on your Igaware Linux Small Business Server then Out of Office can be set either in Outlook, or through the Zarafa web mail.
If you are just using the standard email server on the Igaware Linux Small Business Server users can manage their Out of Office notifications by logging onto a web page on the Igaware server:
https://serverip/config/USERS/vacation.php?username=xxxx
Note: serverip is the IP of your server e.g. 192.168.2.252 and xxxx is your user name.
Simple 🙂