By Reshma Kapadia

NEW YORK (Reuters) - EarthLink Inc.'s ELNK.O arsenal for luring away subscribers from its online rivals includes a multimillion-dollar marketing campaign and new access software that will block pop-up ads, one of the most frequently cited annoyances on the Internet.

The Internet service provider on Monday unveiled the software upgrade and $10 million plus ad campaign as it steps up efforts against competitors Microsoft Corp.'s MSFT.O MSN and AOL Time Warner Inc.'s AOL.N America Online.

Unlike those companies, EarthLink derives almost no revenue from advertising.

"Advertisers would not like subscribers having that option," Yankee Group analyst Rob Lancaster said.

Both Atlanta-based EarthLink and MSN have been aggressively trying to woo away dissatisfied AOL users with tools to reduce junk email and pop-up ads, for example.

"The whole notion is really around switchers and providing a better Internet experience with fewer drop-offs, pop ups and spam," Karen Gough, EarthLink's executive vice president of marketing, told Reuters.

America Online, the market leader, has reduced the number of pop-up ads its members see and replaced promotions on its welcome screens with more member-focused news and content in an effort starting this summer, a spokesman said.

Beginning Monday, EarthLink is making a preview of the pop-up blocker software available through its Web site and will soon incorporate it into the latest incarnation of the company's TotalAccess 2003 software.

FIRST MAJOR UPGRADE IN NEARLY THREE YEARS

"The pop-up blocker is the most exciting feature," said Jim Anderson, vice president of product development. "About 4.1 billion pop-up ads are served on the Internet, and we have had consumers tell us that is the most annoying experience on the Internet."

If users want pop-up ads, they can turn the new feature off, Anderson said.

TotalAccess 2003, the first major upgrade of EarthLink's access service since 1999, also has new e-mail features that let users reach stored e-mail address books from any Internet- connected computer and enable quicker access to services that include games and Google's search engine.

EarthLink, which has about 4.9 million subscribers, will spend more than $10 million on television and radio spots, print and online ads, and direct mail.

While the company's earlier campaigns tried to build awareness, Gough said this one aims to differentiate EarthLink from other Internet service providers.

Most Internet service providers, including AOL and EarthLink, have been struggling with slowing dial-up growth and increasing their high-speed subscribers.

High-speed services are seen as the next major growth engine for Internet companies as Web surfers seek out faster connections and services such as the digital delivery of music.

EarthLink developed the latest version of its Internet access service with high-speed subscribers in mind, Anderson said.

A spokesman said the company plans to upgrade the service more frequently, perhaps twice a year.