I’ve got couple of emails and everyday in addition to usual emails, I also get some newsletter, marketing emails, reading digests, deals and offers and some spam. I open and read some of them and just leave some others unattended.

One day, as I was going through pile of my emails to figure out which ones I should check and which ones I should leave as is, I started wondering …. How many emails are sent everyday in the world? How many of them are spam? How many of them are not needed anymore and don’t get opened? ….. hmmm I’m wondering How much energy is being consumed for all these emails everyday? If I unsubscribe from those I don’t need anymore, will there be a reduction on consumed energy and storage on email servers .. hmmm … I’m wondering what would be its implications on our environment? Would it help to create a greener and cleaner Earth?

So I started researching to find my answers …

Current Situation of Emails

Email is the most popular and most used service of the Internet. Currently, more than 300 Billion emails is sent and received each day and it is expected to increase every year[source]. Some of them are useful and expected emails, some we don’t need anymore, and some we didn’t ask for it in the first place and are spam. Some we open, read and reply, some others, we may not open them at all.

Every email needs energy for basically two things: routing and storage. “routing” is getting the email from sender to receiver. This usually involves multiple servers to store temporarily, establish a network connection with the next server and pass along the email and its attachments to it. When the email reaches to its destination server, it is usually stored indefinitely. That means multiple servers need to be up and running(consume electricity) in order to route emails and store these emails.

I was wondering how much carbon every single email produces .. The carbon footprint is a common metric to measure the amount of gases something emits. The carbon footprint for an email is shown to be like:

 Spam emails: 0.3g
 Typical emails: 4g
 Long emails with attachments: 50g

hmm .. So every newsletter that I unsubscribe and don’t receive anymore will save 4grams of CO2!

But is it worth it?

let’s see …

Let’s say I get around 10 emails each day that I’m not interested anymore. That is 10*4=40g of CO2 emitted each day to send and receive these. Throughout a year, it becomes about 14.5Tonnes of CO2! That’s almost equivalent of 30 plastic water bottle added to the nature! Or the emission of driving a car for 52km! [Source]

And all this is only for an average person. Multiply that by the number of people using email around the world …

But those servers are always on, aren’t they?

Yes, they are on 24/7. But modern servers in data centers have an advanced energy management system that lets them to reduce the amount of energy they consume based on the load they are handling. Some servers can even shrink their hardware capacity size when they don’t have high traffic or when they are idle. So less traffic means less energy consumption for the servers involve in emails.

Golden question

So I started to go through the newsletter emails I get and ask myself “Do I still want this?”.

The ones I answered with “No”, were the ones I unsubscribed. Since then everyday when I get an email and I realise I don’t need that anymore, I scroll down, find the “Unsubscribe” link and unsubscribe myself.

What about those I might need in future?

There were some emails I couldn’t just unsubscribe. Some occasional offers, some informational emails, some digest emails, etc.. For those ones, I decided to reduce the frequency of it. Maybe to monthly, semi-annually or even annually.

What about the marketing campaigns?

I think it’s good for businesses as well. They will have more focused marketing emails that reach to the people who still want it. After all, in todays world, advertisement and marketing is highly focused on a target group and not just mass-sending to everyone.


Sending and Receiving emails emit CO2 as well. We can reduce the emails we receive to help reducing the CO2 emitted for that. That might not seem too big at the beginning, but it adds up to a big number. Unsubscribing from newsletters, digest emails, membership emails that we don’t need and are not interested anymore, can impact the reduce the carbon footprint.