Platte River Networks worked for Colorado Governor John Hickenlooper – once heavily tipped to be Clinton’s 2016 running mate – during his election to be mayor of the city in 2003

The company’s controversial vice president of sales David DeCamillis is also said to be a ‘big Democrat’ supporter who offered his house to Joe Biden for the party’s convention held in Denver in 2008.

It will be the small scale of the firm and its own home-made arrangements which will raise the most significant questions over security and over what checks Clinton’s aides made about how suitable it was for dealing with what new transpires to be classified material.

Daily Mail Online spoke to former employees of the firm, including Tera Dadiotis, who was a customer relations consultant between 2007 and 2010.

Describing it as ‘a great place to work, but kind of like a mom and pop shop’, Tera reacted with disbelief that her former company was hired to manage the email system of Democrat juggernaut Hilary Clinton.