The Facebook Moments app will be required for those hoping to have the social network privately upload photos from their smartphone. Facebook users are receiving an email from the social network asking them to download another of the company's apps if they wish to continue using a service that syncs their photos.

Facebook users will have to install and log in to the company's Moments app by July 7, or else have all their photos inside that album deleted.

The app allows for private uploads of photos for sharing with friends without actually putting them onto the social network. Before Moments, Facebook put into its main app a similar feature called Photo Sync, back in 2012, which, when turned on, automatically uploaded photos from a smartphone into a private "Synced from phone" album.

If you "don't want to download Moments, you will also be able to download a zip file of your synced photos from your Facebook profile on your computer before July 7th," the company said in a statement.