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Save the Planet: Replace Email Attachments With File Share Links

Second part in a series critically examining our continued reliance on the 40-year-old technology of email attachments

Like an old diesel motor, the email attachment technology developed in the 70s and in pervasive use today, is spewing millions of tons of CO2 into our atmosphere. Recent estimates attribute around 50g of CO2 generated from each email carrying an attachment [1]. The carbon impact results largely from the infrastructure needed to transmit and process the message like the data centers which consume electricity to store, transfer, process and analyze the content of the message.

Although 50g of CO2, less than the CO2 of an imported banana (80g), might not seem much by itself, what makes email attachments ultimately so noxious is the number that are sent unnecessarily [1]. In a previous article, we estimate that each professional ignores on average 6,000 file attachments per year. The common corporate practice of copying (Cc, Bcc), needlessly shares files that go unread; threatening data security, challenging information governance and lowering productivity. If we align these same statistics with CO2e (carbon dioxide equivalent) emissions we uncover some staggering revelations.

one year of unread email attachments is equivalent to the CO2 of driving a car 1,093 miles … per office worker

The average office worker receives around 144 irrelevant messages per day, of which 24% have attachments [2,3]. Email attachments sent in copy are accessed only 6% of the time [4]. Given each email attachment causes 46g of CO2 emissions we can easily calculate that unread email attachments generate 1,494g of CO2 every day for every worker [5]. Over the course of a year with 261 workdays, the yearly CO2 footprint of unwanted-unread-ignored attachments creates around 390,000g or close to half a metric ton. How much is that? Well, according to the EPA the average passenger vehicle in the U.S. gets 24.9 mpg. Each gallon spews 8,887g of CO2 [6]. This means that one year of unread email attachments is equivalent to the CO2 of driving a car 1,093 miles … per office worker … (being clear, the unread attachments)!

Person on a laptop & a car, both spewing CO2
Yearly CO2 emissions from unread email attachments in the workplace per employee equivalent to driving a passenger car 1093 miles

Put another way, in a median NYC office building with 1,000 workers, ignored email attachments generate 37% the amount of CO2 as does the entire building. So we can spend hundreds of thousands of dollars improving our insulation and installing solar panels, or it might be more ecological to simply start eliminating unneeded email attachments [7].

Building emitting CO2 through unread email attachments
Metric Tons of CO2 compared — NYC Office building vs. Unread emails

How do we stop sending ignored attachments, you might ask? This is simpler than you think. Users can replace attachments with cloud storage links. Cloud storage is readily available to most office workers, whether OneDrive, Google Drive, Box, Egnyte or other cloud content service. With any of these services, recipients don’t receive attachments, rather links to files. Delivering a link ensures file distribution to only those 6% who actually want the attachment, which eliminates the aforementioned resource consumption and CO2 emissions with the added benefits of containing data sprawl, enabling large file transfer, and decreasing security and information governance risks. Trouble with user adoption? User training or services like mxHero can help by automating the conversion of attachments into cloud storage links.

The email attachment is a file sharing technology of yesteryear, inefficient from its inception, turned destructive by modern day usage patterns

Email has proven a very adaptable medium of communication. However, its success is largely due to its inheritance from the letter (among the oldest forms of communications) and the fact that it is an open protocol that has no owner. Despite its amazing ability to adapt to decades of technological advance, parts of its architecture, like file attachments, are failing badly to keep up. The email attachment is a file sharing technology of yesteryear, inefficient from its inception, turned destructive by modern day usage patterns — patterns completely unimaginable to its creators. It is time for society to collectively “snap out of it” and assume the mantel of change. The alternative is here in the form of shared file links. The costs of inaction is real. We pay the price in inflated security, governance, infrastructure and environmental costs. Time to move on. No more email attachments.

Edit Nov. 5, 2021

Calculate and download the source spreadsheet for CO2 emissions resulting from email use in your own organization:

mxHERO Calculator


  1. How Bad Are Bananas?: The Carbon Footprint of Everything, Mike Berners-Lee

  2. Forbes

  3. Radicati

  4. Crescent Electric

  5. As per source Berners-Lee (1), an email without attachments produces 4g of CO2 while an email with attachments produces 50g. CO2 of only attachments is therefore estimated by subtracting the difference between the two or 46g. As per sources cited here: 144 (Cc, Bcc email messages) x 24% (% of emails w/ attachments) x 94% (% of attachments received in copy that go unread) x 46g CO2 = daily CO2 grams per employee from unread attachments (1,494g)

  6. EPA

  7. Average square footage of office space per person (TMC). Median CO2 for an NYC office building (Urban Green Council)

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