From the Mozilla Blog:
Firefox Send (send.firefox.com) is a free encrypted file transfer service that allows users to safely and simply share files from any browser. Additionally, Send will also be available as an Android app in beta later this week. Now that it’s a keeper, we’ve made it even better, offering higher upload limits and greater control over the files you share.
Send uses end-to-end encryption to keep your data secure from the moment you share to the moment your file is opened. It also offers security controls that you can set. You can choose when your file link expires, the number of downloads, and whether to add an optional password for an extra layer of security.
Send makes it easy for your recipient, too. They simply receive a link to click and download the file. They don’t need to have a Firefox account to access your file.
Read the Complete Announcement