Yahoo currently offers 1 gigabyte for its free mail service and 2GB for its premium fee-based service. Google's free Gmail service offers more than 2.5GB of storage, and Windows Live Hotmail offers 2GB for free.
"We are watching the trend lines of how people are using e-mail...and they are sending more photos and videos and rich media," said John Kremer, vice president of Yahoo Mail.
Google began the storage wars in earnest when itwith 1GB of storage. Yahoo Mail, which launched in 1997 with 4MB of storage, shortly after Google's Gmail announcement, bumped it up to , and then .
With 250 million users, Yahoo Mail is the largest global e-mail provider and the largest in the U.S., according to comScore.
The unlimited storage will begin rolling out globally in May, and Yahoo expects to have all of its customers covered within a month, except for China and Japan. "We will continue working with these markets on their storage plans," Kremer said.