"Starting today, you'll be able to view all your mail at once, regardless of which account it's from, using the new 'All Inboxes' option," Google software engineer Regis Decamps said in a blog post.

"This way, you can read and respond to all your messages without having to hop between accounts."

The new app will aggregate email from rival services such as Yahoo and Microsoft Outlook, among others.

Gmail had allowed users to access multiple accounts from desktop computers, but the new app aims to seamlessly integrate the various email services in a unified inbox with search and preview capability.