A review of the historic domain registration records for that domain indicates that whoever built the private email server for the Clintons also had the not-so-bright idea of connecting it to an Internet-based printer. The subdomains attached to that Internet address was.wait for it. printer.clintonemail.com. A security researcher in California said printing things to a printer set up this way might have made the printer data vulnerable to eavesdropping. Any emails or other documents that the Clintons decided to print would be sent out over the Internet.”]
Source: https://krebsonsecurity.com/2016/05/did-the-clinton-email-server-have-an-internet-based-printer/