using iCal with Zoho mail

using iCal with Zoho mail

I have a Zoho mail account feeding into my Mac and use Mac's native Mail and iCal programs as the front end. Currently, I am not using Zoho calendar.

An associate sends a .ics invite. iCal adds it to my calendar but I cannot send an acceptance notificaiton because iCal says Zoho doesn't have a CalDAV server. Is there a way to set things up so I can utilize iCal with Zoho the same way I do with my Gmail and iCloud accounts?