Forbes’ Gordon Kelly looks at the moves by Google to transition users away from Gmail to its newer ‘Inbox’ service. Gmail is arguably one of Google’s key services on the internet, including mobile, and the Mountain View team needs to be careful.

Desktop users of inbox are now being redirected to the service when they log on to gmail.com. It’s a tiny step in a transition process that could fundamental affect Google’s user base.

The good news is any user who doesn’t want Inbox to replace Gmail has the option to “Turn it Off” which pushes both services back to their dedicated domains.

That said, what’s quite clear is: 1. After 14 months of testing, Google clearly considers Inbox ready for prime time, and 2. In repositioning it over the gmail.com URL, Google sees Inbox as a replacement for Gmail rather than the separate service it has been until this point.

Many Android users will be aware of the Inbox application, available as a separate download from the Google Play Store.

It offers a mix of email, time management, diary alerts, and scheduling. Think of it as Google Cards with far more integration to your Gmail account and you’ll get the idea.

It certainly helps Google understand its users more, which would lead to better returns from mobile advertising through targeting, but it also alters one of the key selling points of Google to the average user – Gmail – and of course it affects the Google Account that is used by everyone to sign on to their smartphones.

A slow burn to change the eleven-year-old service is under way, but Google must tread carefully, it can’t afford to lose Gmail users from the desktop, or make Google Accounts less attractive to Android users.