Email attachments are the lowest common denominator despite the 25MB cap, occasional diversion into a spam folder, no sender authentication, no encryption, poor

Email attachments are the lowest common denominator despite the 25MB cap, occasional diversion into a spam folder, no sender authentication, no encryption, poor suitability of email clients and servers for bulk file transfers, etc. Whatever can hope to replace it must be as popular (network effect), as easy to use, and free. Sharing very large files (hundreds of MB to multi-GB) is too costly for a free service. People will not setup or maintain a server, an always on PC is less reliable and has a slower uplink than data centers, and smartphones have limited data quotas, storage and batteries. Slow IPv6 deployment, middleboxes (firewalls, home CPEs) makes efficient p2p connections difficult. If it's free there's little incentive for a company to spend the money developing the easy UI and marketing it to critical mass. Even simple to use Dropbox has not made a significant dent. BitTorrent never became mainstream at the level of email but it did incentivize people to seed with the prospect of pirated content. The MPAA/RIAA have deputized any websites that accepts user content as copyright police and demonize non-enterprise file hosting services. In a way the success of Facebook is a reflection of the spammy, phishing/malware filled, and slow nature of email and difficulty making your own website; if email continued to improve there wouldn't be demand for a modern solution. File syncing and sharing should be integrated into the operating system. However Microsoft's OneDrive and Apple's iCloud are inferior to Dropbox so a third party solution is still relevant.