It is others' mail address to smartphone?

In the Internet access service for smart phones of NTT DoCoMo, troubles, like a mail address will replace someone else freely thing for 20 days occur, and the affected person is expected to go up to 100,000 people at the maximum.

In the company side, it concludes that it is because the server which manages a user's information was not able to process data, and hurries the measure.
It said that a smart phone will cause the operation which it is going to re-connect all at once if connection goes out, but the above amount of communications that a system can usually process occurred, and processing beyond the server's capability has generated it", and it was explained that it was because a lot of communication beyond the throughput of the system concentrated.