I-mode telephones come with an e-mail address that matches the handset's telephone number, which makes them easy targets for bulk mailers who can send millions of e-mail messages from Internet-connected computers to random I-mode address for no charge.
Users are left to wade through a mountain of spam every time they open their e-mail and, because of I-mode's charging structure, have to foot the bill for downloading such mail to their telephones. All of this has DoCoMo's users, who collectively send 80 million messages and receive 100 million messages per day, complaining to DoCoMo.
So far DoCoMo's response has been minimal. Newspaper advertisements in several major Japanese national newspapers had diagrams and instructions showing users how to change their e-mail addresses and how to block e-mail from certain senders.
Keiji Tachikawa, DoCoMo president and chief executive officer, repeated the advice earlier this week.
"We do realise that this is a problem," he said at a news conference. "Basically do not use your phone number as your e-mail address. I have myself received spam mail and I have changed my e-mail address. I do realise this is inconveniencing our users but all I can really do is ask our users to change their e-mail."
But the company may have to do better than that.
The government is now looking into the issue of unwanted e-mail after the number of complaints received by the Electronic Information/Communication Division of the Ministry of Public Management, Home Affairs, Posts and Telecommunications (MPHPT) regarding junk e-mails via wireless Internet services suddenly increased in March and April, according to Yoshitaka Yano, a MPHPT counsellor.
The MPHPT has requested all domestic mobile telecommunication carriers to take measures to prevent their customers from receiving spam. The request was issued to DoCoMo and its competitors, including DDI, which operates under the Au and Tu-Ka brand names, and J-Phone Communications.
DoCoMo concedes that asking users to change their e-mail addresses is not a sufficient response to the problem of junk mails and the company is reviewing the situation, according to spokesman Norio Hasegawa. The company receives up to 200 inquiries a day regarding the matter, he said.
"Setting the cell phone number as an e-mail address has been done because it is easy for a user to start the e-mail service immediately after the registration," Hasegawa said. "And we cannot track down those senders because the privacy of communication is protected by the (Japanese) constitution."
Other carriers, however, do not suffer to the same degree as DoCoMo.
DDI, which has the second largest market share in the wireless Internet market, uses a different system. Since the launch of its EZWeb service, it has equipped handsets with blocking filter functions and has been making its customers create their own e-mail addresses when they start the service, according to spokesman Hiroshi Ishihara.
"But we still have ten or more inquiries a month from our customers regarding junk mails and try to take care of them," Ishihara said.
Visit NTT DoCoMo at http://www.nttdocomo.co.jp/ .