Who invented email?

Ray Tomlinson invented email as we know it in 1971. He was working on ARPANET communication software when he figured out how to send messages between different computers on the network, not just within one machine. His big innovation? The @ symbol. He used it to separate the user name from the destination computer (user@host), and that addressing system is still how every email works today.

Before Tomlinson, there were local mail systems that let people leave messages for each other on the same machine. But he was the first to make a message jump between computers, which is what turned electronic mail into actual email.

You might've heard Shiva Ayyadurai's name attached to this question. He built an email system in 1978 and called it "EMAIL", but it only worked within a single organization's local network. Tomlinson's version came seven years earlier and was already networked across ARPANET. The historical consensus is clear: Tomlinson invented email.

Why does this matter for deliverability? Because Tomlinson's @ addressing structure is the foundation of every authentication system you use today. SPF, DKIM, and DMARC all authenticate based on the domain after that @ symbol. Understanding how email addressing works helps you understand why authentication matters, and why your sending domain's reputation is so tied to deliverability.