Is email green?

CO₂ Emissions from Email

A single email generates an estimated 0.3 to 50 grams of CO₂, depending on its size and complexity:

• Plain text email: ~0.3g CO₂

• Standard email (with small attachments/images): ~4g CO₂

• Marketing email (rich media, tracking, attachments): 10-50g CO₂

• Spam email (which is sent but not read): ~0.3g CO₂

These estimates account for energy used by data centres, networks, and devices for transmission, storage, and reading.

Annual Email CO₂ Emissions in the UK

The UK sends an estimated 64 billion emails per year. If we assume an average of 4g CO₂ per email, the total CO₂ footprint is:

64,000,000,000×4g=256,000,000,000g=256,000metrictonsofCO264,000,000,000 \times 4g = 256,000,000,000g = 256,000 metric tons of CO₂

That’s equivalent to:

• Over 125,000 round-trip flights from London to New York

• Driving over 640 million miles in an average petrol car

The actual impact could be higher due to rich media-heavy emails and tracking pixels.

How Senders Can Reduce CO₂ (While Improving Deliverability)

Reducing email-related carbon emissions aligns with best practices for email deliverability and engagement. Here’s how:

1. Send Fewer but More Relevant Emails

• List Hygiene: Remove inactive and disengaged subscribers. This reduces bounces and spam complaints while cutting unnecessary emissions.

• Segmentation & Targeting: Only send to engaged users. Less volume = lower CO₂ and better inbox placement.

• Sunsetting Policy: Remove non-responders after a defined period to avoid wasted sends.

2. Reduce Email Size & Optimize Content

• Limit Image & Attachment Sizes: Large images and attachments increase CO₂. Use web-optimized formats and host large files externally.

• Minimalistic Design: Avoid excessive HTML bloat, embedded videos, and heavy GIFs.

3. Use Efficient Infrastructure

• Choose Green Hosting & ESPs: Some email providers power data centers with renewable energy. Look for carbon-neutral options.

• Optimize Sending Infrastructure: Reduce retries and use efficient MTAs like Mailgun. This prevents wasteful re-sending of undelivered messages.

4. Educate Recipients on Unsubscribing

• Encourage Unsubscribing Over Ignoring: Inactive users should be removed instead of receiving emails they won’t engage with.

• Enable One-Click Unsubscribe: Easier opt-out improves list health and reduces wasted sends.

Final Thoughts

Sustainable email marketing benefits both the planet and deliverability. By sending fewer but better-targeted, optimised emails, businesses reduce emissions, improve inbox placement, and increase engagement.

Would you like help auditing an email program’s carbon footprint or implementing greener email strategies? Give ClearPath Deliverability a shout!