The effect is small and poorly understood. According to the authors of a Canadian study from 2022, deleting 1,000 emails avoids about 5 gCO2e. For 1,000 emails of 1 MB kept for 10 years in 6 copies, ADEME's storage reference point gives about 14 g and its email calculation rules about 1 kg. Sorting your inbox remains useful for freeing up space or finding a message. Keeping your devices for longer has a better-established effect: according to ADEME, manufacturing a laptop emits 182 kgCO2e.
Read the source article: Carbon footprint of an email: about 2.5 gCO2e for 1 MB