They kept their domain. This was reported in 13:39 and by 18:21 they recovered their domain, so this was a five hour outage. The issue was they used a registrar that had no enterprise-level support. They have since learned this lesson.

This didn't affect customers that opted for custom domains, either. You shouldn't have a @zoho.com email - register your own domain and have a @sixtram.com email instead (custom domains is offered in the free tier, something Gmail doesn't offer)