Yahoo! users are spending an average $110 (£70) more on their energy use a year than Gmail users, according to American analysts.
The average Yahoo! Mail household in the States uses 11% more electricity per year than a Gmail household.
Data analysts at US energy use tracker Opower looked at whether there was a link between email address and electricity usage of their 2.8 million customers.
The difference is 939 kilowatt-hours – which Opower number crunchers say is almost a whole extra month of electricity, which at an average going-rate of 11.8 cents/kWh, or $110 per year.
Though Yahoo! users appear to live in larger homes, they also use more electricity per square foot than Gmail users.
This could be because Gmail users are more likely to be younger, single people, suggested the analysts on an Opower blog, citing research which shows their average age is 34 compared to Yahoo! users’ 38 years.