The update on Yahoo Mail will also make its look simple as in the mobile phone versions and in sync with social networking sites Facebook and Twitter, a spokesman said Saturday.

The redesign, which had been announced earlier this year, is expected to keep U.S. competitors at bay and cut rivals' lead overseas.

In the U.S., Yahoo Mail is the most popular e-mail service with 97 million unique visitors in August, according to research firm comScore Inc. The figure is twice the combined unique visitors of Google Inc.'s Gmail and Microsoft Corp.'s Hotmail. In August last year, Yahoo Mail had 107 million unique visitors in the U.S.

However, Yahoo Mail is only second to Hotmail in terms of worldwide visitors. In July, Hotmail had 355 million visitors, Yahoo Mail had 281 million visitors and Gmail, 185 million visitors, comScore said.

The Microsoft figure is 3 percent up from the year-ago level while the Gmail number is 22 percent higher than the same period last year. Yahoo Mail's visitors was 7 percent lower than July last year.