Wright calls it a vicious cycle, pointing out that although we act like victims of our own inbox, we all add to the problem. "We often use email to avoid talking to real people or getting started on a top priority task," he says. "The result is constant disruption and actions slipping through the cracks."

Used by Dell, Sony and Cisco, AtTask aims to add collaboration and chat functions, ostensibly to increase productivity. "Email's days are certainly up when it comes to the best way to manage work," says Wright. But until another option becomes universally popular, email is not going anywhere.

Yet the "evidence" persists that social media and instant messaging are eating away at enthusiasm for email in our personal lives.

"I have seen a significant decrease in the usage of emails," says Roger Goodwin, managing director of US-based specialist web development house Digital Trading, which works on software integration projects for clients such as Capita and Siemens.

"Neither of my teenage sons uses email except for password reminders and account confirmations. All other communication is done through instant messaging on their preferred social media."

There's a time bomb under email. "As time moves on and the now-teenagers start to populate businesses, there will be a shift towards this new way of communicating, but it will take some time, and will, in most cases, work alongside traditional email," Goodwin says.

Others say the "email is dead" story is one popularised only by those in Silicon Valley who smell a business opportunity. "Email is a set of protocols and not a single 'app', so there's no way for any single company to develop full control over it," says Alex Moore, CEO of California-based Baydin, whose Boomerang plug-in for Gmail, Outlook and Yahoo! allows users to schedule emails. "Like mobile messaging, most of these new virtual workplaces require you to channel all of your communication through a single server, which means there are a lot more opportunities for a company to extract rent if they can build up a large enough install base."

But virtual workplace software platforms that are fully interoperable? "That looks a lot like email," says Moore.

Instant messaging and social media are incredibly popular, but there are many different platforms that don't talk to each other. It's a kind of like the Wild West: it's yet to settle down. "As a platform, email is a consistent format, everyone uses it, and every device has the ability to collect, view and respond," says Goodwin, who thinks that IM is too dynamic, with messages harder to index and retrieve than emails.

But that hasn't stopped several companies trying to persuade businesses to turn their back on email in favour of bespoke project management software, such as Slack, Podio or Jive, all of which involve instant messaging.

"The role of email is changing from delivering message and content to become a notifier of activities happening elsewhere," says Jon Froda, co-founder and director of Podio brand strategy at Citrix, which has offices in Hong Kong. "It's similar to what happened a few years ago, where email helped people transition to using Facebook," he says. Active Facebookers email a lot less, but does that mean offices should run social media platforms instead of internal email systems?

"Email presents a very linear form of communication that is falling behind the times in the modern workforce, and if businesses rely solely on email, they run the risk of siloing knowledge into individual departments and restricting cross-practice creativity," says Wim Stoop, senior product marketing manager at Jive Software in California.

Others think our dependence on email at work is problematic on a more human scale. "For too long, businesses have operated within a culture of 'I have sent an email; therefore, it is no longer my problem'," says Scott Cairns, chief technology officer at global telecoms company T-Systems, Deutsche Telekom's corporate customer arm, which has offices in Beijing. It recently issued a paper called "Social media: the slayer of email?".

Highlighting the spread of "no email Friday" policies that encourage more talking and less typing, Cairns thinks instant messaging from the likes of Yahoo, Microsoft and Google provide a halfway house alternative to emails.

"While instant messaging should not replace all face-to-face interactions, where a few seconds could be taken to ask a question and receive an answer without having to break from the task at hand, it is a good use of the technology," Cairns says.

T-Systems operates an internal social network that tries to mirror how its employees interact in their personal lives.

"There may still be the requirement for external email communication, but with social platforms evolving at a rapid pace, the final piece of the puzzle is just round the corner," Cairns says.

Exactly what that final piece looks like is anyone's guess, but it's already obvious that email inboxes are changing; most already include elements of instant messaging. The ideal platform would combine instant messaging with "presence awareness", video and - crucially - email.

So is the future of online communication still email? "As technology evolves and changes so quickly, I am certain that a combination of instant messaging and email will emerge that offers the best of both worlds," says Goodwin.

"It will no longer look like a single inbox," says Moore, who thinks that deep learning, voice and image recognition will soon help us in ways that go far beyond sorting our email into categories.

Instant messaging and social media still have room to grow, but as communication tools they're mere limbs; email is the backbone of the internet. Email has no limits; it's customisable and universal. It's therefore one of the last reminders of what the internet was supposed to be before it became splintered, and packed with protocols competing for dominance.

Whatever communications platform appears next from Silicon Valley, we already know it won't be as popular as email.