Comment by Insanity

Someone explain to me why this matters please. The emails (passively) stored on HDD/SSDs in a data centre wouldn't be the main contributor to heat generation and the needs for cooling.

What would probably increase heat and the need for cooling more meaningfully is actual data transfer and processing (i.e, reading and sending emails). But even so, compared to all the other internet activities (streaming video, gaming, AWS/Azure/GCP).. it's probably a drop in the bucket.