SAN FRANCISCO — Yahoo’s free e-mail service is becoming a bit more like Google’s Gmail as part of its second makeover in less than a year.
The similarities to Gmail probably aren’t coincidental. Yahoo CEO Marissa Mayer helped design some of Gmail’s features while she was a top executive at Google Inc. Since its debut nearly a decade ago, Gmail has grown into the world’s most popular e-mail service.
Yahoo’s redesigned e-mail unveiled Tuesday includes a Gmail-like tool that will thread together e-mails related to specific topics so they appear as a succession of messages. The ‘‘conversation view’’ has become a widely used e-mail feature since Gmail helped popularize the concept after it embraced the format in 2004.
Users can turn off Yahoo’s new conversational tool if they want.
Another new feature will enable Yahoo’s e-mail users to decorate their inboxes with a selection of scenic pictures plucked from the company’s photo-sharing service, Flickr. Gmail has been allowing its users to spruce up their inboxes with various themes for years.
When Yahoo’s e-mail users choose a picture as their backdrop, the same look will automatically appear on the mobile e-mail applications that the company is modifying as part of the redesign.
The updated apps are for Android devices, Apple Inc.’s iPhone and iPad, and tablets running on Microsoft Corp.’s Windows 8 operating system.
In another change, Yahoo is now promising each e-mail account a maximum of one terabyte, or about 1,000 gigabytes, of storage.
The Sunnyvale, Calif., company says that amount should be enough to cover the storage needs of its average e-mail user for about 6,000 years. Yahoo Inc. had previously promised its e-mail users that they would never run out of storage, but it hadn’t established a specific limit.
Gmail vastly expanded the capacity of e-mail boxes in 2004 when it rolled out its service with a limit of one gigabyte per account.
At the time, industry-leading e-mail services run by Yahoo and Microsoft Corp. were limiting storage on their free accounts to 25 megabytes or even less.
Yahoo’s terabyte limit now dwarfs Gmail, which has a per-account limit of 15 gigabytes that also includes material kept on Google’s Drive and Photo Plus services.