Gmail is by far the most popular email service, with more than 1.5 billion active users.

Its recently published app "privacy label" has revealed that those who grant the appropriate permission to the iOS Gmail app can expect Google to share information including their approximate location, user ID and data about the ads they have viewed online with advertisers.

Just how private is Gmail compared to other email services such as Microsoft Outlook and Yahoo Mail?

Andy O'Donoghue joined us for Tech Tuesday to discuss this.