1. Log into your Roundcube mail interface using http://webmail.domain.com
2. When you are successfully logged in, go to Settings.
3. In the settings menu, select Filters, you create a new filter on the bottom of the filter.
4. Click on Roundcube -> Create -> For Scope , choose all Messages with Actions -> Reply with Message
5. Give the filter a name eg "Out of Office" and for message body, please type the message you want to send send on the out of office reply.
5. To enable and save this filter, TICK on the Filter Enabled box. This will make the out of office reply enabled.
6. After this is done press Save.