Yahoo! (Nasdaq: YHOO) is upgrading its e-mail service to appeal to mobile users, the company’s first major product announcement since Chief Executive Officer Marissa Mayer took the helm, pledging to improve tools and services to lure back customers.

“Email is the ultimate daily habit. It’s often the first thing we check in the morning and the last thing before going to bed. Why? Because it’s one of the simplest and most basic forms of communication. And since it’s such an important part of our daily lives, we’re making a few improvements to Yahoo! Mail,” Mayer wrote in a blog post announcing the changes.

“You’ve told us loud and clear that you want fewer distractions when it comes to email. You want to quickly login, communicate, and get on with your day. And we’ve listened. Starting today, the new Yahoo! Mail is fast, easy and available anywhere you go. These improvements will be available on all major platforms: Web, Windows 8, iPhone/iPod touch and Android.

“We’ve redesigned the new version of Yahoo! Mail with speed in mind — getting through your emails is faster than ever before. We’ve also made your inbox more intuitive and easier to navigate, allowing you to focus on what matters most: your messages. And, because mobile is everything these days, Yahoo! Mail now has a consistent look and feel across devices.”

Mayer, a former Google Inc. executive, is seeking to reverse three straight annual sales declines by updating existing widely used products, including mail, the Yahoo Messenger chat service, and Yahoo’s home page. The efforts are poised to stoke competition with her former employer, which has added millions of users to Gmail as Yahoo Mail has stagnated.

Versions of the new e-mail will be available for smartphones and tablets running software such as Microsoft Corp.’s Windows 8, as well as Apple Inc.’s iPhone and iPad and machines powered by Google Inc.’s Android operating system.

Yahoo products have failed to keep up with changes in online habits, the CEO said on a call with analysts in October.

Internet communication is “primed to be re-imagined,” Mayer said on the call. “There is great opportunity to modernize Yahoo Mail and Messenger, especially given the continual increase in the amount of communication we’re all receiving.”

The CEO has said she plans to invest in hiring engineers with expertise in mobile applications, boosting the company’s technology for buying and serving ads, and building services that are more personalized for individual users.

Mayer kicked off her Yahoo comeback strategy by hiring several senior deputies, including Henrique de Castro, previously Google’s vice president of global partner business solutions, as operating chief. Mayer promoted Adam Cahan, founder of a social-TV startup acquired by the Web portal last year, to lead mobile services at the company.

(Bloomberg contributed to this report.)