This has been happening for a few months now, with first reports going back to February:
The lasts reports are dramatic — some people tried to get help for a few weeks now as their company mail has been barely accessible. The issue appears to be random — a small percentage of domain names is affected. Google Support hasn't addressed the problem yet, even though users started organizing initiatives such as this one:
One technician had a bad luck and almost got fired, when he persuaded his boss to switch company's mail to Google, and then had the corporate domain affected.