The Do Not Call site lets people register their telephone number with the Federal Trade Commission to prevent telemarketers from calling. The FTC levies monetary penalties if marketers continue to call the registered number.
"We knew it would be popular," said David Torok, Do Not Call project manager for the FTC. "But we've had overwhelming demand on the site. We were logging in 1,000 transactions per second, and by noon 370,000 users had registered."
Access to the Do Not Call site was intermittent Friday and the site took roughly 28 seconds to load, said Roopak Patel, an Internet analyst for Keynote Systems, a Web performance and load-testing service company. Patel said access to the registration form itself, from the site, was also intermittent and took about 15 seconds.
"The two sites together magnify the unlikelihood that the transaction will be completed," Patel said.
AT&T, which the FTC contracted to manage the Do Not Call site, is adding more servers and configurations to handle the heavy traffic, Torok said. A representative for AT&T referred inquiries to the FTC.
Even those fortunate enough to get through to the site and register Friday had trouble. For some--ironically--the desire to block unwanted marketing calls was tripped up by the blocking of unwanted marketing e-mail: Internet service providers either routed the Do Not Call registration confirmation e-mails to users' junk-mail folders, or prevented the messages from reaching in-boxes, due to the way users set up their spam-blocking filters.
If users fail to respond to their e-mail confirmation within 72-hours of its being sent from the Do Not Call site, their telephone number will not be registered, Torok said.
"E-mail confirmation is important," Torok said. "We have notified all the ISPs, because we knew the confirmations could be affected. For Yahoo, these e-mails are being sent to users' bulk e-mail filters."
Yahoo spokeswoman Mary Osako explained the situation on Friday.
"These e-mails are currently being delivered to users' in-boxes," Osako said. "Our antispam technology is purposely designed to detect unusual and extraordinarily large volumes of mail-sending behavior. We adapt our systems as appropriate when we become aware of legitimate volume-senders of e-mail, which applies in this case. Upon learning of the situation, we promptly initiated communication with the e-mail service provider that the FTC is employing to seek-out needed information so that we could adapt our systems."
Yahoo rivals MSN and AOL also commented on the problem.
"Mass-generated e-mail, even if it's generated by the FTC, can look like spam," said an MSN representative. "Consumers, depending on how they have their spam folders set up, may find their mail redirected to their junk folder." The representative noted that MSN recommends that people periodically look in their junk e-mail folders to make sure legitimate e-mail isn't being lost.
AOL spokesman Nicholas Graham said some AOL members are not receiving their registration confirmations because AOL's spam-blocking filters are preventing the e-mails from reaching in-boxes. As a result, Graham said, AOL users who do not receive a confirmation notice within 72 hours of submitting their registration should re-register at the Do Not Call site.
In a posting to a list for network administrators earlier this week, Richard Callahan, client business manager for AT&T Government Solutions, warned in an e-mail: "Every registration using the Web generates an e-mail which must be opened to complete the registration process. We are looking at the potential of millions of e-mails per day beginning Friday. I am worried about denial of service, or blocking by spam filters if providers are not aware this is coming."
Torok advises users who have not received a confirmation e-mail within 72-hours to register by phone at (888) 382-1222. Torok stressed that the Web site and phone service will be available for many months to come and that users should not feel pressed to register today.
Some states have seen 40 percent of wired telephone users sign up for anti-telemarketing registries in their regions. Torok said he anticipates similar interest among the 166 million residential telephone users in the United States. By year's end, he said, the FTC expects 60 million people will have signed up for the service.
CNET News.com's Rob Lemos contributed to this report.