The US computer programmer came up with the idea of electronic messages that could be sent from one network to another in 1971.
His invention included the ground-breaking use of the @ symbol in email addresses, which is now standard. Tomlinson died of an apparent heart attack on Saturday, according to BBC reports.
He sent what is now regarded as the first email while working in Boston as an engineer for research company Bolt, Beranek and Newman.
The firm played a big role in developing an early version of the internet, known as Arpanet.
However, Tomlinson later said he could not remember what was in that first test message, describing it as “completely forgettable”.
His work was recognised by his peers in 2012, when he was inducted into the Internet Hall of Fame.