"You're either focusing on the emails exclusively or you're compromising your understanding using a variety of different strategies to partially understand the gist of the emails," he said.
Professor Reichle's research, published in Macquarie University's The Lighthouse, used computational modelling and eye-movement experiments to understand the mental processes involved in reading.
He said readers had to look at least 80 per cent of the words they read to understand them.
It takes 150-to-300 milliseconds to identify words and about 150 milliseconds for eyes to move between words, which means there was an upper limit on how quickly we can read and accurately comprehend information.
"If you're reading something really light like a Stephen King novel, you can read 300 to 400 words a minute easily and have pretty much full comprehension," he said.
"But if you start reading faster than that, you’ll be missing parts of the text, not identifying words or not parsing the sentences correctly."
Professor Reichle also dismissed claims by speed reading gurus of reading up to 10,000 words per minute as "bullshit".
"That's physically impossible because of the limitations of visual acuity and how quickly you can identify words and physically move your eyes," he said.
Professor Reichle said the speed at which someone can read and fully comprehend will be affected by the complexity of the information and the quality of the writing: "To the extent that you're skimming emails, you're going to risk missing something or misunderstanding."
Finance broker Aaron Christie-David said his team of four at Atelier Wealth used to receive more than 400 emails a day and spent up to three hours sorting through their inboxes.
"We would spend most of our day replying, cc'ing and forwarding emails," he said. "When would we get any real work done?"
Mr Christie-David's company now uses a virtual assistant to prioritise, categorise and archive emails as well as calendar apps to organise meetings.
"Our VA ensures that we have the coveted 'inbox zero' at the end of each week," he said.
Professor Reichle said email had many advantages but could be overwhelming if not properly managed.
"I routinely get emails from people whose office is down the hallway from mine," he said. "Rather than getting up and coming over to ask me something, they'll put a question in email."
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Professor Reichle's research has ramifications beyond highlighting the need to manage your inbox.
He said researching eye movements was an attempt to understand the perceptual, cognitive and motor processes involved in reading, which could ultimately assist people who struggle with literacy.
"Reading is critically important for literate societies," he said. "Reading skill is predictive of income level, health and longevity so understanding why some people very easily learn to read and some don't is important."
Andrew Taylor is a Senior Reporter for The Sydney Morning Herald.