Let me update the status as of today:
Yesterday (Feb 27th) we identified root-cause of the problem and were working with some of the customers and hosting vendor to restore the service back to normal level.
As of now (Feb 28th) we have fully restored Antispam Service from our EU datacenter.
In a mean time this case triggered discussions with hosting vendor and currently we are working on additional agreement with them which will let us to prevent such cases from happening in the future. I hope will send you updates on this topic soon (once it will pass through technical and legal reviews :-))