Google plans to increase the inbox storage of its Gmail web mail service from 1GB to 2GB, and it will continue to raise that ceiling in coming weeks and months, on a rolling basis, to unspecified heights.

"Since we introduced Gmail, people have had a lot of place to store email, but some of our heavier users have been approaching their limits and have been wondering what's going to happen," says a Gmail spokesperson. "So, starting on Friday, we're going to give people more and more space continuously and indefinitely on Gmail, as we're able to technologically."

There are no current plans to increase Gmail's 10MB limit on attachment sizes and there are also no plans to add capabilities to Gmail that would allow subscribers to turn the inbox storage into a full-featured virtual external hard drive.

However, Google is aware that some Gmail subscribers are using the service for this purpose, mailing files to themselves to have them stored in their Gmail inbox, says the spokesperson.

The percentage of Gmail users approaching their inbox storage limit isn't large, but "they are a number that we care about," he continued. "We want our users to understand that we have a plan and that we're anticipating their needs, and that there isn't something strange that's going to happen with Gmail down the line."

When it announced Gmail a year ago, Google rocked the web mail market, whose main players generally offered minimal inbox storage for their free services. For example, at the time, Yahoo offered its free web mail users 4MB and Microsoft offered MSN Hotmail users 2MB of inbox storage.

Since then, most major web mail providers have reacted to Gmail's inbox offer and have increased their storage significantly. Microsoft and Yahoo now both offer 250MB for their free services, and Yahoo plans to begin offering 1GB starting in late April. Both Yahoo and Microsoft offer 2GB inboxes with their fee-based web mail services.

A caveat with Gmail is that it is still technically in a beta, or test, phase. To obtain a Gmail account, one has to receive an invitation from an existing user; each current user has 50 invitations to give. Google also randomly offers Gmail accounts via its main Web page.