We have restored all Zoho services. They should be working normally. Our teams are monitoring the situation closely, and if you encounter any trouble, please let us know.
We know this is not what our customers and users expect from Zoho. We let you down today. Please accept our humble apologies. We have launched a full investigation of the root cause, how we responded to it, what we could have done better to both avoid the problem and how we could have resolved it sooner. We will post this report as soon as it is ready.
Update: Our preliminary information is that reverse DNS look up failed in one of our subnets, which caused the outage on some of the services. We still are trying to determine why it failed, why it didn’t trigger other type of alerts and why this failure resulted in such a service outage. Once the incident is fully understood, I will post a detailed report.