Last updated: 21 July 2026
How MailBroom estimates the CO₂ impact of freeing mailbox storage, tracked as a running total on every account and available as a badge for your own site.
The estimate
Stored data has an ongoing energy cost — the servers and cooling that keep it available. MailBroom applies a fixed 0.233 kg CO₂ per GB of storage freed to estimate that impact, the same figure used live in a MailBroom account's CO₂ counter and in the ROI calculatoron this site. Treat it as a reasonable, consistently-applied estimate — not a certified measurement of any specific customer's actual server footprint, which depends on factors (data centre efficiency, redundancy, backup retention) MailBroom has no visibility into.
In your account
Every account tracks lifetime CO₂ saved alongside storage freed, emails deleted, and time saved — moving through award tiers as the total grows, from Seedling up to Earth Hero.
An admin can opt in to a badge showing the organisation's aggregate CO₂ and storage savings, embeddable on your own site and updated automatically — off by default, and never exposes individual employee data.
Freeing mailbox storage reduces the ongoing energy cost of storing and backing up that data on Microsoft's servers — less data held means less storage capacity and associated power draw attributable to it. MailBroom estimates this at 0.233 kg CO₂ per GB of storage freed, the same factor used in the account dashboard's live CO₂ counter and the ROI calculator, treated as a reasonable estimate rather than a certified measurement of any individual customer's actual server footprint.
Storage freed (in GB, from Smart Sweep deletions and unsubscribes) is multiplied by a fixed 0.233 kg CO₂/GB factor. This is the same calculation shown live on a MailBroom account's dashboard and used in the ROI calculator on this site — one consistent figure across the product, not a different number per page.
Every account tracks lifetime CO₂ saved and moves through award tiers as that total grows, from Seedling up to Earth Hero — a running total tied to the account, alongside storage freed, emails deleted, and time saved.
Yes — MailBroom for Business includes an embeddable badge showing your organisation's aggregate CO₂ and storage savings, updated automatically as the totals grow. It's opt-in (an admin has to explicitly enable it) and only ever shows your organisation's aggregate totals, never individual employee data.
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