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10 ways to make your email marketing more sustainable

When email marketing was first introduced it was seen as the sustainable alternative to direct mail and producing print. And it is true that individual emails use relatively small amounts of energy to send. However, processing, sending, receiving, and storing the contents of emails builds up. According to Statista, more than 347 billion emails were sent every day in 2023 and that is expected to increase to over 408 billion daily emails in 2027 (Statista, Global e-mail audiences).

In Mike Berners-Lee ‘How Bad are Bananas?: The Carbon Footprint of Everything’ (2020), he estimates that any one email can generate between 0.03g and 26g of CO₂ emissions. “In the grand scheme of things, the impact of email is not the biggest carbon problem humanity faces, but it is an easy one to tackle. Berners-Lee acknowledges that thinking about email is a good way into conversations about ‘the benefits of cutting every kind of junk out of our lives’.” (The Carbon Cost of an Email).

Emails are part of the greater digital ecosystem for which the energy requirement is growing exponentially year on year:

The good news is that by focusing on sustainability for your email marketing you are also aligning your email marketing activity with email marketing best practice. This means that developing more sustainable email marketing practices leads to maximising engagement, reducing unsubscribes, and increasing your impact.

Here are our 10 top tips to see if you can be more sustainable AND increase your email response rate, push up your conversion rate, and improve your return on investment.

1. Staying relevant

Email marketing works – it is the best performing digital marketing channel because it is targeted. The key to maximising response rates and being sustainable is by being relevant to your audience(s).

Even healthy open rates of between 20 – 30% still mean that most of your contact list hasn’t opened your email. These unopened emails represent wasted energy for you and for the environment.

Tracking and testing can guide you and help you anticipate what your audience wants when. Whether you are looking at the frequency of your emails to avoid over-mailing; fine-tuning your targeting/segmentation; and/or developing and testing new content, having a testing strategy will help you understand your audiences better. Test, track, and test again.

2. Segment your audience

As your list grows, segmentation can help you focus your messaging and reduce wasted effort and energy. Segmentation is an essential tool if your offer is multi-faceted, and you have a number of clearly differentiated audiences to engage. Size of audience and workload capacity will help you decide how many segments you create.

Segmentation can start right at opt in form stage as with this example from the Arnolfini gallery:

Screengrab of a newsletter sign up form from Arnolfini gallery

Alternatively, it can be incorporated further along the customer journey such as in this automated email from Greenpeace:

Screengraph from Greenpeace website reading 'Greenpeace, we know all the issues we work on are important and interconnected but, if you had to pick just one, which would you say is the most important to you? Ending plastic pollution, Protecting forests, Ending air pollution, Stopping climate change, Creating ocean sanctuaties

Using a preference centre where contacts decide what content they want to receive can help to further support your segmentation. A preference centre can be key to staying relevant to your audience, and once set up, has little or no impact on workload. Ensuring that people can opt out of content that they aren’t interested in saves you time, money, and is more sustainable.

3. Only talk to people who are interested

The opt in permission-based sign-up model for email marketing means that your contact list is made up of people who have given permission for you to contact them. By definition they should be interested in your brand or organisation, and your content.

Evidence shows that double opt-in creates leads that are more engaged and that have a higher customer lifetime value. (Double opt in is where a contact signs up for an email marketing list, and then an email is sent out to the contact which includes a link to click and confirm the subscription.) Having a larger number of engaged subscribers is great for your marketing impact and by its nature is more sustainable.

Inevitably over time, as contacts’ circumstances change or interest wanes, a proportion of your list will become part of your group of inactive contacts. Estimates for customer attrition rates are on average 25% per year: this is the percentage of contacts who stop reading your emails. Removing inactive subscribers from your contact list has multiple benefits including reducing your carbon footprint, pushing up your conversion rates, and saving your money.

Since average attrition rates run at 25% of contacts per year, it is important to realise that running a regular data hygiene or reactivation campaign is essential to remove inactive contacts from your list. Remember, any data held on servers has an impact on your carbon footprint – reducing the quantity of data that you store is not only more environmentally friendly but can also help you save money.

4. Reduce image size

Using the right size images can make a significant different to the carbon footprint of your email and its download speed. Resize images to the dimensions you intend to use in your email.

Equally, changing file formats can reduce the ‘weight’ in terms of CO2 of an email. If you want to prioritise sustainability and have the smallest file size possible, then JPEG images use a 10:1 compression ratio. PNG images are higher quality, but they are much larger once the compression image is completed. JPEGs are not the best option for images containing text, however for accessibility reasons, we recommend avoiding using images with text in emails wherever possible.

5. Run regular reactivation campaigns

A reactivation campaign targets your inactive contacts. On average successful reactivation campaigns will re-engage 10% of inactive contacts (Salesforce). Running regular reactivation campaigns enables you to ‘scrub’ your contact list – removing your inactive contacts. These campaigns can be set up as automations, also known as triggered emails, that run in the background and are sent as a series of emails. Here is an example from the Royal Academy:

Screengrab of reactivation email from the Royal Academy

Contacts who haven’t opened or clicked on your emails over a period of time and who don’t respond to your reactivation campaign are not useful to you. These contacts are costing you carbon and money. Under GDPR, let your inactive contacts know that if you don’t hear back from them, they will be removed from your contact list.

6. Use UTMs for tracking

Email marketing works best when it drives clicks through to good quality content on your website. Open Rates have been affected by Apple’s Privacy Policy which masks whether a contact has actually opened an email and reports it as opened regardless. This means that open numbers can be inflated. Clicks however are a genuine measure of engagement and drive traffic to your website which helps to build lasting customer relationships.

Using UTMs (Urchin Tracking Module) can provide more detail and insight on your website tracking reports. A UTM is text added to the end of a URL to track the metrics and performance of that specific link. Using UTM codes in your email marketing enables you to track specific email performance and engagement, including conversions, revenue, sessions, page views etc. Better insight can help you be more efficient, focusing in on activity which generates results and impact, reducing wasted effort and wasted energy. Read more in our article on ‘How to use UTM Parameters to track marketing activity’.

7. Build-in sustainable email design

There are a number of design tactics which help accessibility, improve the look and feel of your emails, and are still environmentally responsible.

Using responsive design, when your design adapts to the size of the device screen, and testing your emails before your send, ensures that your email displays correctly on all devices and screens. According to latest stats from HubSpot, 46% of people are accessing emails on mobile. Having an email that is easy to read and doesn’t need re-downloading means its accessible for all and saves energy.

Dark mode is a reversed colour scheme. It changes the user interface so that instead of seeing the traditional dark text on a light background, there’s light text on a dark background. Research on email engagement from Sinch indicates at least 25% of consumers view their inbox in dark mode. In terms of sustainability the jury is out on whether dark mode offers any significant energy saving. However, given that people may be using dark mode, test your emails in dark mode to ensure that your messages are legible and that your graphics aren’t disappearing into the dark background.

8. Avoid unnecessary automations

Email automations generate better open and click rates than batch and send emails. This is because they are sent on an individual basis with tailored, timely messaging. Welcome emails can generate up to 90% open rates.

For sustainability, when designing your automations, consider ways to reduce unnecessary emails by adding in filters. For example, avoid reminders that are sent to people who have already opened and/or responded. Although automations take time to set up and test, they perform well and are generally low maintenance once they are up and running. Watch our ‘Introduction to email marketing automations’ webinar.

9. Video use and optimisation

Using video presents a dilemma: video is a data intensive format leading to a larger carbon footprint. But evidence shows that including a link to video content in your email can boost engagement. Our recommendation is to make sure that video is genuinely adding value to your comms. If you are using video, ensure it is properly sized, optimised, and as short as it can be. Always use a third-party video host (such as YouTube or Vimeo) which is configured for optimal compression. This has the advantage of universal access – everyone will have the same experience across all devices and browsers – and compression reduces the time and energy required to load them.

10. Email Expiration Initiative

To go the extra mile, it may be interesting to consider something like the Email Expiration Date initiative (EED). The EED enables email senders to set an expiration date on the emails they send, so that these emails get automatically removed from the inbox once they become irrelevant (billions of emails are stored indefinitely in data centres around the world, burning energy unnecessarily). This will happen either because the sale or offer is over, or because the content of the email is no longer relevant.

Although this idea has been considered previously, the EED Initiative aims to bring mailboxes, Email Service Providers (ESPs), and brands together so email expiration dates can be realised. There are still some unanswered questions about the implementation of email expiration dates – mostly linked to its compliance with regulations like GDPR. Read more about the Email Expiration initiative campaign.

In conclusion

The Act Green 2024 report found that 74% of audience members said a sustainability accreditation would make them view an organisation more positively. Making your email marketing more efficient, engaging, and accessible, benefits both you and the planet.

If you are a creative or cultural organisation or individual in England and would like any support around sustainability and/or email marketing, please book a one-to-one meeting: book a phone call or video chat to discuss email marketing.

Next step: Read the Digital Culture Network’s ‘10 ways to make your website more sustainable‘.

Further information

Why your internet habits are not as clean as you think – Article from the BBC’s Smart Guide to Climate Change

What Are Ethical Email Providers? – Ecosend article about what to look out for to ensure your email provider is considering environmental sustainability

Health Check your Email Marketing – Digital Culture Network resource

Further support

The Digital Culture Network is here to support you and your organisation. Our Tech Champions can provide free one-to-one support to all creative and cultural organisations who are in receipt of, or eligible for, Arts Council England funding. If you need help or would like to chat with us about any of the advice we have covered above, please get in touch. Sign up for our newsletter below and follow us on X (Twitter) @ace_dcn for the latest updates.


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