By Martin Dobson, AIERT Ltd
I had 50,000 emails in my inbox. Not because I'm disorganised — I'd just never really thought about deleting them. They were just there, sitting quietly on a server somewhere, not hurting anyone.
Except they were. Every email we send, receive, and — crucially — store has a real, measurable carbon footprint. I only started thinking about this properly when I added it up.
A standard email generates around 4 grams of CO₂e. One with an attachment? Up to 50 grams. To put that in perspective: sending a 1MB photo to ten people is roughly equivalent to driving 500 metres by car.
Scale that up globally. In 2018, 281 billion emails were sent daily — generating roughly 410 million tonnes of CO₂e annually, comparable to half of commercial aviation's total emissions. By 2025, that figure had risen to 376 billion emails per day.
The storage problem compounds it further. A 1,000-employee company sending 40 internal emails a day generates approximately 58 metric tonnes of CO₂ per year — equivalent to 13 cars on the road annually. And that's just from internal email traffic.
The obvious solution is an email cleaner. But most of them — the ones that work in the cloud, syncing your inbox to their servers for processing — paradoxically make things worse.
Research from UC Riverside and Qualcomm found that on-device AI processing reduces emissions by 75–95% compared to cloud alternatives. When a cleaner uploads your email data to process it remotely, it's burning server energy on top of the energy your emails already consume.
Data centres currently account for around 0.3% of global emissions — and that share is growing. Traditional email cleaners address clutter while ignoring their own carbon impact.
I looked at what was available. Most email management apps fall into one of two camps: they're either cloud-based (and therefore energy-hungry by design), or they're basic tools that just help you manually sort things. Neither solves the problem properly.
What I wanted was something that could intelligently identify what to delete — newsletters, promotions, duplicates, old receipts — and actually execute the cleanup at scale, all without ever sending my email data to a third-party server.
That's why we built MailBroom.
MailBroom connects directly from your iPhone or iPad to your mail server — Gmail, Outlook, iCloud, BT, or any IMAP provider — over an encrypted connection. Your emails are classified entirely on your device using a five-layer AI pipeline. Nothing is sent to our servers. Nothing is processed in the cloud.
One full cleanup of a 50,000-email inbox saves approximately 200kg of CO₂ over the lifetime of those emails in cloud storage. That's the equivalent of not driving for two weeks.
MailBroom includes a permanent free tier: 5 Smart Sweeps and 5 Storage Cleanups, no credit card, no time limit. That's enough to make a meaningful dent in most inboxes.
For unlimited access, MailBroom Pro is available at an introductory price of £0.99/month, rising to £1.99/month after the introductory period. No lock-in — cancel any time through your Apple account.