We’re friends, you and I (and a billion other people).

Facebook isn’t exactly the most trusted company when it comes to user privacy. A new policy might be cause for concern for some users. Facebook is now allowing premium advertisers to target their campaigns based on mobile numbers and email addresses.

The new functionality, currently being tested among select advertisers, will require advertisers to upload their own customer lists, which may include email addresses and mobile numbers. Said functionality was temporarily available in the Power Editor tool, reports Inside Facebook and is accessible through a “Custom Audiences” tab.

Facebook has pointed out, though, that this feature will not give advertisers any additional information over what they already have. The functionality will only match Facebook users with the email address, user ID or mobile number that an advertiser already has on their own database.

The feature has been in private testing for some time now, and will soon roll out to users with access to Facebook Premium.

Is Facebook going too far in ad targeting? Is ad-targeting through mobile numbers, user ID and email address an affront to user privacy, or will these help Facebook improve its user experience by ensuring social network users only see ads that are likely to be interesting?