The world's most popular email service is stripping the storage limit on its free email. In response to the increase in the size of email attachments such as large media files, Yahoo is one-upping rivals Google and Microsoft, Reuters reports.

Unlimited storage for Yahoo email will become available to Yahoo's quarter of a billion email users beginning May 4. "We are giving them no reason to ever have to delete old emails," Yahoo cofounder David is quoted as saying. "You can keep stuff forever."

Yahoo's unlimited email storage plan would trump Microsoft's, which offers a 2-gigabyte free email storage limit, and Google Gmail's, which gives users 2.8 gigabytes of storage.

One caveat: Yahoo says the unlimited storage offer is for personal use and subject to guidelines against abuse that apply to Yahoo Mail. For one, it won't allow the building of a business giving away unlimited storage to other consumers using Yahoo Mail, executives said.