Ray Tomlinson does not recall the contents of the first e-mail that was ever sent.

He thinks it was probably QWERTY, or another meaningless set of letters produced swiping one's hand across the top of the computer keyboard.

Whatever it said, at around 7pm one autumn evening in 1971, the first message using Mr Tomlinson's fledgling software, known then as the 'Send Message Program', travelled the short distance of a metre from one computer to a neighbouring machine, and electronic mail was born.

Since its beginnings in a computer lab at the offices of a firm in Cambridge, Massachusetts, e-mail has become one of the most important communications platforms the world has known, and from the various services available – Yahoo!, Hotmail, and the ubiquitous Outlook – Britons send an estimated three billion messages a day.

But it has also given rise to the menace of spam or junk e-mail, which most of us spend 52 hours a year sorting and deleting, according to one estimate, and armed cyber-criminals with one of their most highly effective weapons, capable of proliferating viruses and even reducing the computer systems of entire Governments to a flickering mess.

Did Mr Tomlinson have any idea quite the havoc - not to mention large-scale criminal enterprise - his creation would be capable of unleashing?

"Absolutely not. At that time, the number of people who used e-mail was very small - maybe between 500 to 1,000. So if you were getting spam, you'd know who was sending it. You'd be able to say to them: that's not a good thing to do."

"It was only when e-mail came to be widely used that the possibility of sending a message anonymously emerged," said Mr Tomlinson, who is 66 and today still works for BBN Technologies, the company in whose employment he achieved the breakthrough that would bring the world closer together, aged 29.

He said he doesn’t feel too guilty, though. "Spam certainly is a problem, but at the time I just didn't think about it. E-mail is like any tool - it can be used for good or bad. If you’re looking for a way to spread a virus with a computer, then you’re going to use the most popular communication tool - and that’s e-mail.

In the early seventies, Mr Tomlinson was one of about a thousand researchers working with the US Department of Defence on the development of a network called the ARPANET, the precursor to the internet.

One problem he had with the first e-mail program was finding a way to separate the person to whom one was addressing a message from the computer or network they were using – which he solved with the symbol @.

It could just as easily have been a square bracket or even a comma that would come to be typed in every e-mail address, “but they were already being used, and of the characters that were left, @ was best. Plus it conveyed a sense of place, which seemed to suit.”

It took another 20 years – until the advent of the world wide web in the early nineties - before e-mail became widespread, but Mr Tomlinson said that the basic characteristics of most modern e-mail programs – commands for deleting, replying and forwarding, and folders – were in place back then. “They’ve just become a lot bigger and bulkier nowadays.”

He uses Thunderbird, an e-mail application developed by Mozilla, the company which distributes the Firefox web browser, but he also has a Gmail account.

He said he once had to use Outlook – “I didn’t find it particularly attractive”, and that for a time he blocked all incoming messages from Hotmail, “because they used to carry a lot of viruses – though they’ve clamped down on that.”

For someone who invented e-mail, Mr Tomlinson is not a prolific communicator. He sends a modest 12 messages a day, and reads 40-50.

Does he think, given the development of other forms of electronic communication such as instant messaging and social networking, that his creation will stand the test of time?

"I suspect possibly we’ll see a morphing of e-mail and other, more instant methods," he says, "but there will always be a need for people to be able communicate asynchronously, that is, send messages that won’t be read or replied to immediately, and that’s what e-mail allows you to do.”

E-mail in numbers

170 billion: Number of e-mails sent worldwide each day

2 million: Number of e-mails sent each second

49 minutes: Average time an office works spends each day managing e-mail

34: Percentage of internal company e-mails that office workers say are ‘unnecessary’

30-40: Number of times per hour workers check their e-mail

(Sources: Radicati Group, Gartner, Times Database)

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