AOL puts pop-unders on the night shift

America Online will begin limiting pop-under advertisements linked to its AOL Instant Messenger service on Thursday, in order to target at-home rather than at-work audiences, according to a company representative.

The Internet service provider said it has been delivering pop-under ads--usually promotions that spring up behind requested Web pages--for some time to members of its instant chat application, AIM. That means AIM users receive third-party pop-under ads without opening a Web browser, which are typically the source of the ads. The promotions appear instead beneath AIM Today, an informational AOL pop-up that's also launched when users open the application, but the company limits the delivery of pop-unders to one per day, per user.

"Effective tomorrow, (we) will only run them after 7 p.m. (We find that users at work find them particularly annoying)," AOL spokeswoman Ruth Sarfaty said in an e-mail.

Pop-unders and their more intrusive sidekick, pop-ups--ads displayed over requested Web pages--have been the source of massive frustration for Web surfers in recent years. As more Web publishers have tied their content to them, more visitors have chosen to install pop-up blocking tools. Despite such technology though, advertisers and software makers have still found ways to get around the blockers, and it's often hard for Web surfers to pinpoint the source of the pop-ups.

In recent years, Google, Yahoo, MSN, AOL, Earthlink and many others have introduced technology to help people thwart the ads. Just this week, AOL's own Netscape Communications launched products to mitigate pop-ups and spam, as well as scan e-mail for viruses. As a result, as much as 30 percent of the Internet population uses a pop-up guard, according to estimates from ad technology companies.

Many mainstream Web sites have also stopped allowing the ads. MSN and Yahoo say they limit the ads to specific areas of their sites. AOL has scaled back the sale of pop-ups, too, so Internet service subscribers won't be bothered.

Yet other publishers willingly allow pop-ups or pop-unders because they command higher prices, and they're in high demand by advertisers. Ad executives say they can cost advertisers $10 per thousand sent, or more for popular sites. That compares with between $2 and $3 per thousand for a static banner ad that appears on the same popular site.